Timing Belt : Undo bolt while under tension ?

[jsteele22]

Okay, I've been reading up on the timing belt job, and the one thing that isn't clear is : do you actually unbolt the tensioner wheel while the belt is under full tension ? It looks/sounds like there isn't any provsion for releasing the tesion from the belt before-hand. (e.g., on a Saab, there's a hole that a 1/2 " breaker bar fits into, so you can compresss the tensioner in situ). It sounds vaguly dangerous, so I wanted to check before I undo any "loaded" bolts.

TIA,
Jeff