I don't think you need the bios to run msx1/2 roms
I think that the cbios v.025 is already preloaded with the emu.
the only reason I know this is because I managed to get it to run games even though I had put the bios in the wrong folder!
Also I could only get the openmsx.opk to run from the internal memory, I could not get it to run from external sd card.
I think you need different bios if you want to run disk or tape games though.
They go in the usr/local/home/.openMSX/share/systemroms folder
Hope this helps!