I encountered this problem just today, not from a pattern but because of how I decided to increase the first time for mitten thumbs. I did pretty much just what you said, suzeeq, and it worked just fine. I'm glad to know I did it *right*.
Cheating is an option. . . . Cheaters never win and winners never cheat, but smart knitters who want to retain an iota of sanity do, cheerfully. ~~Kory Stamper