So I think I did the best I could.
I used virtualbox commands to use the physical drive as a VMDK. I used BeOS to partition the drive, but OS/2 probably would've worked also. 3 primary partitions, 4 logical. I discovered it really doesn't matter. I installed BeOS and OS/2 in primary partitions, as well as the OS/2 boot manager that really wants a primary partition. I setup partitions for KolibriOS, Slackware, Haiku, and XOSL (just in case).
After competing the setup of OS/2, and installing the BeOS boot manager, it worked. I could use the BeOS boot manager to boot the OS/2 partitions. Finished up, but the drive in the laptop, and... no luck. Doesn't load either OS/2 Boot or Install partition.
Im sure there is an answer, idk what a different computer or drive would change. I have only been able to get it working on a virtual machine with a virtual drive or physical drive.
I used XOSL. It takes over the MBR, while also being installed in a logical partition. It also cannot boot the OS/2 partition or OS/2 boot manager, however, it can boot "Original MBR" which boots the OS/2 boot manager. It works out that way, so I have the 5 operating systems working on XOSL, but it's not as nice and pretty as BeOS boot manager. If the MBR gets messed up, just use the OS/2 CD to set boot manager startable with LVM, or reinstall if necessary. Then use XOSL cd (freedos) to restore XOSL to the partition.
XOSL boots original MBR, BeOS, And Haiku fine. It also boots KolibriOS and Slackware using their own LILO installations.