Based upon my setup with a Asus P6T Deluxe motherboard, running 2 RAID SAS drives, plus a PATA DVD, you can’t get to the LSI MegaRaid bios settings as it tells you in the manual; because the motherboard doesn’t have enough memory.
Solution is to access the BIOS and disable the SAS card (or other bios loading hardware) temporarily and re-boot. You can then get into the LSI BIOS with <Ctrl-H> as prompted on screen. Make the changes and then enable whatever you turned off in the first place. The LSI card will still work even when the web interface for the config hasn’t loaded into the BIOS