So... I think I was actually able to get it to work.
The icons are just temporary until we can come up with something better... but it shows up both in the editor and in the BB Code List, and seems to work. Honestly, I didn't think it was going to work because of how we did it... but apparently it does.
Let me know if there are any problems (or if anyone would like to contribute nicer icons, that'd be cool).