This is not spoon feeding.
FVWM2 2.6.5 is available as a package for OpenBSD 5.2. It is packaged with a message that will display on install or update, and can be repeated by using pkg_info(1) with the -M option.
That install message no longer explains how to set your .xinitrc/.xsession file to use FVWM2. It used to. 26 months ago the message was changed to remove that guidance, though you can find it in the CVS repository for the ports tree, either via cvs(1) or via the CVS web interface at the Project website.
The answer is obvious, and you will have a facepalm moment when you discover it.
