Knitting a vertical buttonhole while knitting in the round?

I’m working on a set of biking gloves and I don’t have a pattern I’m following. Basically i’m knitting using double pointed needles and I just need to know how to make a vertical gap (a thumbhole) while knitting in the round. Does any one know how to do this?
Thanks,
Amy

This is kind of like trying to work intarsia in the round. :thinking: If you use two strands, they end up in the wrong place.

How about working back and forth for that section and then resuming knitting in the round when the gap is finished?