I just had this book from my library - see if yours has it:
Mastering Color Knitting by Melissa Leapman. There was a section, 2 pages or so, called Intarsia in the Round. I only briefly skimmed it, but she talked about a couple 'work arounds' for how to do intarsia in the round. I can't tell you how she did it, as I was in a "check out knitting library books and look at the pretty pictures" mood - not a learn how to do something new mood.
For that matter, try a google search for intarsia in the round and see if you come up with anything.
Mirl56 at Ravelry, too.
Learn from the mistakes of others. You canít live long enough to make them all yourself. Eleanor Roosevelt
Lady Feb Sweater
more shawlettes, socks