I was unable to install from the memstick installer (wouldn't even run live–lua errors and kernel panic) and CD installer (ran live, but couldn't find target device partly through install). Between my hardware and the pfsense USB tools, something is seriously rotten.
What's really odd is that I did once successfully boot (most of) this hardware from the embedded image on USB. Only two things have changed since then, and that is my CPU and my BIOS. I had to update the BIOS to accommodate a newer CPU. Since then I have reset the BIOS to default a couple times, and changed every setting imaginable one at a time, but to no avail.