I'd love to see this play out... more and more of Guybrush being taken over by LeChuck's evil. Personally I'd like to see him become mostly LeChuck-ish (maybe just Guybrush's cunning hair staying

) when he gets executed. Then he'd somehow be able to come back to life as has been previously mentioned. Then I'd like to see a switch to the mostly Guybrush (but maybe just the completely digusting hair of LeChuck staying) Lechuck with Elaine. Elaine has at that point fallen in love with LeChuck and in the middle of a romantic scene LeChuck switches voice roles (and minds) with Guybrush, therefore showing that almost all of Guybrush has entered LeChuck's body. Guybrush in the body of LeChuck sees that he doesn't have much time to get the sponge because he doesn't want to be trapped in LeChuck's body. Move back to the body of Guybrush and see that he is mostly LeChuck now, including his voice and mind that has now changed. LeChuck realizes he doesn't want to be stuck in Guybrush's wimpy body and decides to also search for the sponge. A funny scene to lift the mood a bit could be them realizing they could read each other's thoughts. It would show their reactions, etc. A challenging puzzle would allow you to switch back and forth playing as both people trying to find the sponge until they meet up with each other and team up to find it. It would be really cool in my opinion to see two enemies work together. Eventually they find the sponge in the nick of time before the transformation is complete, etc.
Well that wasn't confusing at all, was it? xD That's how I'd like episode 5 to go.