Originally Posted by Modshack
You only have to remove the transmission if the push rod from the cylinder is completely detached and fallen into the bell housing. You can reinstall a slave cylinder without removing the bell housing if the rod hasn't fallen into the housing during removal. Quoted from JHM's DIY:
"Once it is in, it will drop into a catch on the trans that will hold it in place, at this point just reinstall the 6mm allen (hex) bolt and tighten it down. If it goes in super easily you most likely missed hitting the clutch fork with the push rod. However, if you have a new slave cylinder that you installed or have air in the system for any other reason it will be pretty easy to install."
Granted, this is for Audi trannys and the TT is pretty MkIV VW like. Sorry if the process is drastically different for a TT, maybe someone can chime in with a DIY or description of the slave in a TT tranny. You are correct that I assumed it was similar to a traditional Audi trans. I haven't worked on a TT transmission before, but I've had my share of A4 trannys. Realistcally this is all a mute point because you'll need to call your shop for a proper quote anyhow.