I don't believe there's a way to specifically change the order the disk drive are in per se. The drive order is determined first by order of controller then by order of channel.
Say one drive is on channel 2 of the IDE controller and one drive is on channel 1 of the SATA controller, if the IDE is detected first, the IDE hard drive will come first even if it's on the 2nd channel.
Changing the boot order in the bios will not change this, it will simply change, as it's named, the order in which the drive will boot, not their position.