I followed the instructions in this video and everything was working fine, minus stuttering with FMVs and music in some games, though from what I can gather that seems to just be part of OPL in its current state (please tell me if I'm wrong on that). At one point I wanted to turn the PS2 "Sony Computer Entertainment" bootup screen back on, so I went into Free HDBoot Configurator in the Free HDBoot menu, set "Skip Sony Logo" to "OFF" under "Configure OSDSYS...
Most settings missing from PS2 Free HDboot menu
Most settings missing from PS2 Free HDboot menu