Hmm. I didn't think to change the drive letter in XP first. I think it's not simple as registry issues can happen. I'll go that route and let you know how it goes.
The BeOS boot manager just boots based on partition number. I'm
Not sure what the OS/2 boot manager does. When the windows boot manager is active just booting XP, it's just the default setup with the first partition being C:, until OS/2 interferes. I think if I can successfully get XP booting with D:, I should be all set.
Sorry, not changing drive letter but just boot into the partition you will install OS/2 because this partition already was defined If I correctly understand it. I wrote D: because you wrote installing OS/2 to D: (drive letter is LVM added during install)
Boot one time (from under you boot manager) into the partition you will install OS/2 (if this partition is empty, boot will fail but the boot manager has it taken as boot partition, than boot on the DVD and install OS/2 (it should see the latest boot partition used from under you boot manager)