There's not really a single "high pass loop" there, but rather a bunch of different high basins all clustered together with various passes connecting the different basins (I hate names like "THE Weminuche high route"... uggh) Most of the basins have a faint use trail that departs from the popular trails (such as the ones on the Elk Park/Needleton Loop) and make their way up the basins. Some of these use trails are much more clear than others; some are hard to follow and you're basically off-trail. Most of that hiking is fairly steep too, and downed trees can be annoying. But that's really not harder than what you'd expect for off-trail travel in the mountains. The hardest part is the passes themselves, as most of them are pretty steep and with annoying scree (although they're pretty short for the most part). For the most part, those passes don't exactly require Class 3 scrambling or anything; you'll either be totally comfortable on that kind of terrain (on all the passes) or sketched out on all of them. I'm guessing fosanna didn't feel nervous for a second! (but I sure did!) Since a lot of those passes have similar difficulty level, you could always have a tentative plan of leaving the Elk-Park Needleton Loop to do a variation that incorporates some of those off-trail passes, and if the first pass is out of your comfort zone, you could just backtrack and continue the standard loop.
If you come up with tentative plans for that trip and want to know details about specific passes or basins, feel free to PM me. I've only been to some of those basins, but I'd be happy to share info... I'd just prefer to keep it in PMs
One other note---the small amount of on-trail hiking that I've done there is also spectacular; you don't have to do a "high route" to see spectacular scenery there. I personally thought the trails there were some of the nicest I've been to in CO.