Set IM ''Send" Key to send Message

We are coming off of an IM system, ALTN’'s Comagent, that has a user preferences setting of “Set IM ''Send” Key to send Message".

Many user in our IM network have this option set and don’'t like the fact that they when they hit their enter key, it sends the message.

Would a subscription to the skinning service allow me to change this setting or can someone tell me what file I would need to modify to make this change?

This user selectable option would be an excellent new feature to add to an already amazing IM client.