Sorry for posting after such a long time. I forgot about this thread for a while.
Thank you Vehek! I tried it out, and it worked! I played up to getting Norris with all the codes put together, and everything seems to be in order! Only problem is that characters still call Serge "Lynx" in dialogue, but I imagine that might be because the game might actually write out "Lynx" instead of having a bit of code that says "put the character's name here" since it's impossible for his name to be anything else during this part of the game (just a guess though), and if that's the case, I don't imagine there's any way to fix it short of cracking open the game and manually rewriting the dialogue.
At any rate, thank you so much everyone! I'll play through the game like this and see how it goes. For future reference, and for anybody else who may want to do this, all of the codes to turn Lynx back into Serge are below:
3006EBF5 0000 (character model and menu/dialogue pictures)
3006EBC9 0008 (name and innate color)
8006EC32 00A0 (replace Glide Hook with Dash & Slash)
8006EC4C 00A1 (replace Feral Cats with Luminare)
8006EC5C 00A2 (replace Forever Zero with Flying Arrow)