Mailing the story:

I've been trying to mount a Linux filesystem in OpenBSD 4.2 for awhile, and finally I figured out how to do it (and do it automatically at boot) without screwing up either my OpenBSD or Linux partitions. I have a tutorial on this about 1/2 of the way done, but this was another situation where the excellent OpenBSD FAQ and man pages, as well as a couple of good general Linux/Unix online resources gave me all the help I needed. (I can never remember quite how to make chmod do what I want without looking it up.)