This actually wasn't so hard. Used construction adhesive and my finish nailer (which is a little tricky, you have to get the angle and location just right to replicate the effect you get from a floor gun). One of the things that really hit home doing this whole house project has been how much each phase of construction depends on how well the last thing was done. Imperfect joists mean imperfect boards on the deck and lumpy drywall on the ceiling; poorly hung drywall means sloppy seams when you mud and tape; stringers on the stairs that don't perfectly match mean risers that have gaps where they meet the treads. But you make do.
The risers here are actually just two 4" boards of bamboo, with the top board ripped to size. The treads came from the manufacturer in 6' lengths that I cut to size. I was able to get them all to sit cleanly enough that we won't need to trim out the stairs. (John at Res4 was hoping I could do the landing that way too, but I'm not that good...) Caulking should hide all the gaps. (I've got a LOT of caulking to do; haven't done any of the cleanup on the trim yet, and lots of places outside could stand to be caulked as well.)