I found my own answer. The pass is open year round to bikes, so we are free to ride up there any time. Only cars are prohibited right now. The trick is finding a time when the roads have been cleared of snow but before the pass is opened to cars. This year it looks like that window will be Thursday before noon.
I'm planning to ride from Colonial Creek campground to Mazama and back on Thursday, starting around 9:00am. It should be fun!