According to the plist; Apple Messages is registered to handle the following URL types:
IMSG://
iChat://
Messages://
aim://
xmpp://
im://
I have a quick try and could make Messages appear, but I couldn’t get anything else to happen, hopefully with a bit more experiementation you can figure it out.
Otherwise the Apple Script may prevent your application from shipping on the Mac App Store (technically the Apple Script won’t, but reviewers frequently block apps that use any form of Apple Script).