I just did it but it turned into a bloodbath with dead guards all over.
Tried several times sneaking past but always got spotted, or found a room full of folk I needed to get by - one way or the other.
So it allways ended in bloodshed.

Anyone know if it is possible to sneak past the guards and do it without killing half of Calcelmo's friendsand family?

A) Im a thief and not a buthcher - I want to get the langauge sorted, not "Conan kill maim" everyone.
I'm also a mage and don't want to upset Calcelmo from an RP prospective - "Hi can you give me quests. By the way sorry about slaughtering your guards last week..."
C) I want a house there - I already have a bad rep after a prison escape (I was framed...), so don;t want more undeeded bloodshed.
D) They are house guards not bandits or Draugar, I don't have a problem with them, so don't want to kill them.

You need good level sneak, I used the control rod to get the spider to distract people in the first bit. I had a similar problem to you when I got to the room with the Mage in. But if you sneak into the chamber above there is a lever (or might be a chain?!) if you pull this it turns on all the traps and the guards evacuate along with the Mage guy, leaving you alone until you have the translation. At which point they come back on high alert, and I had to half sneak half run to avoid combat.

i just used the traps to kill everyone. They should have known better than to hang around dwemer traps.

There is a giant spider in the Dwemer excavation site he wants you to kill. If you do this, you get the key to museum. No sneaking required. ALTHOUGH, I did this little quest after completing the thieves guild. I'm not positive that it will work, but it should.

sneak. sneak. sneak. getting in is fairly easy. getting out? invis in a couple spots, either by potion or spell.

edit - oh, and when sneaking....go slow.

I was actually wondering the same thing. My sneak was level 50, I had the first perk in sneak, DB boots on and used an invisibility potion and they STILL saw me the second I rounded the corner. I just assumed that no matter what you're forced to kill the guards. I was able to avoid a lot of the mages guards (or whatever they were called), but the Markath guards were just in the wrong place at the wrong time. *shrug*

its a thieves guild quest so high sneak is something thats expected from you to have, also you can always use invisibility potions or the invisibility spell, soo yeah...

I rushed through, then turned a leaver which caused all guards to flee... getting the translation however was quite easy, once I had it I jumped on some platform and jumped down behind all the guards... sorry for being vague but I completed the quest shortly after 11.11.11.

Use Throw Voice. Comes in very handy in a pinch.

Did it without having to kill anyone. Think I might have singed a couple with one distraction, but got past them and got out without being sighted.
It took time patience good timing, and a few clattering arrows to distract some guards. But it felt really good to do it the thieves way not the butchers way.
Don't get me wrong - down a bandit filled dungeon there will be plenty of bodies once i've been and gone, but back in civilisation I like to pride myself getting the gold and goods without a trail of dead odies to mar my thievish reputation.

I snuck past everyone in the Museum (which I broke into). It wasn't that difficult.

I've done this twice, once on my jack-of-all trades character and once on my dedicated sneaky thief.

I botched it bad with the first guy, and it rapidly turned into Plan B for Bloodbath.

Sneaky Khajit had no issues at all, because his Sneak is in the low 90s and strongly perked out.

I think it's just a pretty unforgiving stealth test.

Yes it is possible. You just have to watch their routine.

Invisibility plus sneak! You said you were a mage, so you should have invisibility. It works. You don't even have to sneak usually. Just make sure you have silent spell casting or they'll hear you invisabilifying yourself and run over to check it out and most likely notice you.

lol that quest is impossible with non-thief char

Well it is a Thieves Guild quest so a non thief character should have trouble.

But it is possible to do without killing anybody as other have already said. I did it with no invisibility pots. It took a while and watching guard routes was nerve racking but it was very rewarding when I finally escaped with the transfer.

I just ran through the whole thing, got the translation and on the way back jumped off the top of the waterfall. Then i left the city and next time i came back no-one was hostile.

I actually though the first major quest was the hardest as it requires you to cross a bridge and navigate through a small confined house. Everything after that was a breeze. it's safest to have level 70 sneak for the silent running perk or whatever it's called in this game. After that, guards walk right up to you and still don't spot you.

find the red wheels, each one you turn either turns on or off a trap-> find the right one and the peopkle in that room panic and run away and even open the door that previously needed a key allowing you to enter the room without fear of being deteced.