walleyed,
I could not find anything about CO requiring the IBEP to bowhunt in CO, but many outfitters do require it to ensure that their bowhunters have a basic understanding of bowhunting and how a broadhead harvests game.
As for finishing the course, all states offer the IBEP under some name, so you can go to any state and take the course and it will be good in any other state or province. Also, some states offer the option of taking most of the classroom portion of the course online and then doing a half-day field experience to finish it out.
Hope this helps,
Larry Schwartz
HS and IBEP instructor