(It's a mod if the SVN disassembly; the built ROM and .lst file are included.)
I'd love to write up a full tutorial and also a conversion for the Hivebrain disassembly, but I'm way too busy (I've been pulling 12 hour days in front of the computer lately and I can't take too much more without going mad). Hopefully it will be easy enough to make sense of for anybody who wants a Wall Jump. Just search the .asm files for the tag "Mercury Wall Jump" and you'll find all the changes I made.
I made the sprite for it from bits and pieces of other Sonic sprites. I really didn't like the Crackers sprite and I think mine is better. Also it uses the same mappings as the Braking sprite so it made it faster to implement.
While I didn't notice that it broke anything engine-wise, it will allow the player to reach areas that they shouldn't. If one were to put this in a proper hack, they'd have to fix the SLZ metatile solidity and a few other things.
It works on solid objects (including the GHZ solid wall) as well as level tiles.
I know there's some resistance to the idea of "giving away code" in the community, but I'm an open source kind of guy. Credit would be appreciated, but as always isn't absolutely necessary.
Specifically, I hope this helps E-122-Psi make a Mighty hack! =)