Disclaimer - I play on the PS3, so I don't have access to any console commands.

I was messing around with my warrior character who is a werewolf / member of the companions etc. I was passing through Labrynthian having just cleared Ustengrav, and remembered back to my mage character who completed the CoW questline and had emerged from Labrynthian victorious with the staff. Now, as I was walking along with my warrior, I saw there were a couple of stones littering the area around the raised level which had the exit trapdoor.

10 minutes later I was holding the Staff of Magnus and Morokei in my hands.

How?

First you need to find a small stone pillar sticking out of the ground at an angle near the raised platform. Jump on top of this pillar, and look towards the mountainous wall. You need to transform into a werewolf at this point to be tall enough to jump far enough to get onto a rocky ridge on the mountain wall (I'm not sure if a particularly tall race like an Altmer would be able to make the jump; I was a Nord and was just unable to). Once on the wall, it's simply a case of angling your jumps and pushing against the wall, causing you to rise up on it a couple of feet. Once you're up onto the top ridge, you can turn around and jump onto the raised platform and enter the non-quest barred trapdoor into Labrynthian - Tribune.

Once inside, you will be confronted with a barred door. My heart sank here, as I was at this point very excited about 'breaking in' to a place the developers obviously didn't want me to. But don't despair! If you slowly move your crosshair around near the centre of the door, or near its edge in the middle, your cursor should momentarily flicker from 'Open Wooden Door' to 'Remove Bar' (or something similar). If you can quickly press X when this happens, you can magically reach through the door and unbar it!

Go through the door and you'll be in some burial chambers, Keep going through and you'll eventually get to a wrought iron portcullis opened by a switch on the other side. Luckily it is very close to the portcullis itself, and reachable through it! It is on the left wall as you stand facing the gate. Get as close as you can and the option to open it will appear.

Follow the corridor down and you'll get to another barred door. Repeat the same trick as before. I found this one was a bit trickier, but was able to get the unbar option just at the right edge of the door. Once opened, you'll find yourself in the Morokei chamber, without having had to clear the entire large Labrynthian dungeon!

Slay the two enthralled mages holding him captive, and the dragon priest will be free and try attack you. Take him down and grab your prizes - the dragon priest mask Morokei and the Staff of Magnus also a treasure chest will appear behind you now beside the door we came through to get here. Also there is a treasure chest in the small pond with the waterfall, but beware - it's guarded by a single Slaughterfish.

But we're not done yet! If you go through the other door to the chamber (the one you would normally have to) you will get to another wrought iron portcullis. Unfortunately this is where the fun ends. However, through the portcullis you'll be able to see a ghostly Draugr (Scourge for me). If you wake it up with a carefully aimed arrow through the gaps in the portcullis, you might be lucky and it will come close to the portcullis to come and get you. If you slay it there, you can loot its Ghostly Remains and get a random Drainspell / Drainheart / Drainsomething weapon .

I was hoping I'd be able to reverse-progress back through the dungeon to pick up the Ancient Nord Helmet of the Unburned, but I wasn't able to find any way to get through this second portcullis . However, I have to say that it was a pretty good haul as it stands . My warrior character didn't have to do the length College quests to get this mask (and to be frank wouldn't really want to) and I really felt like a thief going somewhere he really wasn't meant to! Far more exciting than any of the Thieve's Guild quests, and that's no lie

I'm on PS3 also so I may try the door thing next time I come across one.

Bump

Nice, I was down the trapdoor earlier this week but headed back out when I found the door was barred.
You can get to the trapdoor by climbing in from the left, when facing the trapdoor, and use Whirlwind sprint to jump the last part as well. Just aim at the pillar so you hit that and don,t go shooting past and off teh other side.
No need to be a werewolf.

I too hate having to do Winterhold quests to get at places.

I got the last mask my warrior was missing in that way too. Most one way doors blocked by a bar can be opened that way. It seems there's a collision bug that sometimes will let you reach the bar behind the solid door. Good for those who don't want to go through a long dungeon for the Nth time just to retrieve something at the end.

Well done OP. I love pulling things like that off in the game. Far from being a cheat it is completely in character.

This so works. I am on the PS3 and there is a cletch in the staff of Magnus questline and I could not get Morokei to finishj all the priest masks. I read this "helpful hint on this site several weeks ago and tried it that night. I was in a out in 5 minutes with the staff. I am playing a Nord warrior level 51 and had no issues jumping from the 45 degree slanted stone just in front of the wall to the trapdoor. I am not using it on the other doors but it really helped out in this case because I was stuck since the wounded guy athe dwarfen ruin would not die and give me his notes and keys. Another handy one is the give your follower a lockpick and get real close to them by a locked door that will not let you open it. The follower will say hey or somjthing like that then open the door for you and go in, just follow them in and raid the place.

Meh, I can't 'unlock' the door, the crosshair doesn't change

Have you broken the College of Winterhold questline?

Is there a word wall in there as well?

Yep, but I'm not sure if you'd be able to get it by going through backwards.

Worth a try, anyway.

Yep