I did a Wheeljack leg mod last night using a Reveal The Shield Turbo Tracks that I found on clearance. There are a few different ways you can do this mod that involve Dremmeling the Wheeljack parts, but I didn't want to damage him so I sacrificed a Tracks instead. The final result is pretty rough, but that's fine for me because it's on the rear of the legs and it's just for display. If you want to do a cleaner, more professional job I recommend using a Dremmel to finely grind and shape the parts, rather than hacking away at the plastic with a pair of pliers, which is what I did.
Check out the pics below.
If done correctly this mod does not affect transformation.
It's up to you whether or not you use the Tracks fixed wheels, or remove them and stick with the pivoting Wheeljack wheels. I chose the latter because I don't want to damage my Wheeljack figure. Also bear in mind that if you want to use the Tracks wheels the silver on them is a slightly different shade, which might be noticeable in vehicle mode.