[Kazander]

I've always done this sort of thing using Basic Lift.

Combine the BL of the characters attempting the feat, run it backwards through the formula for BL based on ST {(STxST)/5}, then use that ST for a contest.

e.g.: 3 characters have ST 10, 13 and 14. Their BL is 20lb, 34lb and 39lb, for a combined total of 93lb. This gives an effective combined ST of 22 (rounded up).

Use the Extreme Scores section on B349 to normalize the scores of 22 against 50, to 10 against 23, and roll a Contest.

Obviously, the telekinesis ST 50 has a huge advantage here. This is like Average Guy trying to get past a door being held by Hafþór Björnsson; good luck! The guys with the battering ram aren't likely to get past this.

Better off to use the ram to destroy the door. DF2 suggests combining ST using the Highest score + 1/5 the others for this, to do damage with the ram. A single-person ram is supposed to do Swing + 3d+1; can't find any rulings on multi-person rams.

Or, if appropriate as GM, reconsider that ST 50 telekinesis, down to ST 25 or something, where the PC's have a chance against it.