I looked around a little, and didn't find anything explicitly. I remember from my CO hunter safety course that the instructor defined "hunting", as carrying a suitable weapon (bow, rifle, etc.) designed to take game, outdoors... That sparked all kinds of discussion in the class, but his understanding was that an "affirmative" act on your part was enough to demonstrate "hunting" (unless you were obviously target shooting).
To be safe, I'd give the DOW a call. They have always been very helpful when I gave them a ring. Just be sure to tell them that the rifle will be in a case, unloaded. (Contact Information | Colorado Parks and Wildlife