Seatbelts: removal and color swap

Hello all,
I have an E30 with non-working seatbelts because I swapped in newer seats, and the built in receptacles in the new seats are newer and somehow not compatible. After I discovered this and asked for my receptacles back (supposedly trash), the guy who sold me the seats stopped answering texts.

But I work for a company that makes seatbelts and seats.

This caused me to think two things:

I bet I can put something else in there that will work.

I bet I can swap in some of the neon green web that we have at work. (We have a procedure for buying product, according to another engineer)

I wasn't able to find a DIY on seatbelt replacement online during my lunch break, and I'm bad with breaking trim clips unless I know exactly what's going on. Anybody had the front seatbelts out? How hard are they to pull? What's the best approach to getting that B-pillar trim off?

2 door or 4 door?

4 door.

Edit: managed to save some stuff from the scrap bin today: suitable buckles and tongues, and some burgundy and neon orange webbing. We'll see if I get to put it to use.