I'm finding it cumbersom to keep pulling the handle in and out of the thieves Guild's hideout. Has anyone tryed fast traveling to an interior cell? I was going to try tonight when I got home but I figured someone has tried it.
It'll need a map marker too.

NM. I decided my comment was too off topic.

I got busy doing other things last night and didn't get to try this. real world stinks.

I don't know of a way to make the map marker refer to inside the TG.

You can make a teleporter spell to take you there easy enough though. You could even make it not work in places where fast travel was blocked so as not to make it too useful.

Well I found my answer. DocClox is correct, you can't make a map marker to an inside cell. I don't know how to make a spell but I do know how to make a teleporter. I used 2 standing stones, then disabled their scripts and added my own. I used one of the many xmarkers in the Flagon and the TG hideput and I'm in now. Nice.
I wish I knew how to properly package a mod.