what do you need to access the bios for? I don't think that there is a mac bios, but I could be wrong here. I have never had the need. Are you just trying to install os x on these machines? What are the specs?
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"Fix it 'til it Breaks."

Jacob - EiC & Director of Technology
Mac Pro Quad 2.66 - 4GB RAM
160 GB SATA RAID 1 - 650 GB Storage
Quad 19" Widescreen LCDs
Accessorized to the Hilt