I’m sorry that no one from this forum was able to answer this. I did however find the answer and wanted to share it with you.

Instead of:
Quote:
aim:goim?screenname=+15555551212&message=Hi!

try:
Quote:
aim:goim?screenname=%2B15555551212&message=Hi!

2B is the hex code for a plus sign. When you put a hex character code in a url, it is preceded by a %.
This works like a charm! Have fun with it!!!

-digitalant