FBA,
I don't have a TL-3, but I have had problem getting Pilas to work in some of my lights and the problem has always been one of two things. The first is the button on top being much wider than they are on 123's. That's why I soldered a small button on top to give it a little extra reach. The second problem has been with springs. They either can't get around the thicker Pila bodies, or the length of the Pila screws them up.
First, you need to measure the inside diameter of you battery tube, with a caliper. Make sure that the 17mm diameter batts with comfortably fit. If they physically fit, I don't see why they can't be made to work. The 2X150 will be about 2mm longer than 3X123, so you should probably check this too.
If there is indeed a piece that interferes with the batts and pushes them up preventing negative contact, it sounds to me like you'll need a longer spring. If you get the Pila setup and you can't get it to work, I'm sure that you could move it on B/S/T. It's just hard to discuss a problem when you don't have the elements of the problem in hand, so to speak.