Not gonna fulfill the request by any means; I'm just here to provide a base I had for removing tileset specific crap from slopes which may (or not) be useful Link
It's a (maybe full?) disassembly of the slope code with some adaptations. Good enough for making player-hurt slopes. The file comes with a example block inside.
Images with context behind the files (from SnesLab):  
Slope assist tiles aren't required as those aren't handled by this code.
The routines have the Slope Pass Glitch Fix 2.1
patch baked into the code, but you should be able to figure out which code I added and be able to revert or make toggable the fix.
Nerd talk and other stuff I said regarding this resource can be found on the discord, #qldc-showoff, #qldc-no-regrets or whatever name they change it to. Link to message
The important info is here anyway, so it's not very important what I said there.
There's barely any docs/comments on this, I have no clue how most of the code works and it's been a long time since I did this, which means I will not be able to provide assistance if anyone who takes on this decides to use what I did. Good luck!