OS/2 Museum just published this great article detailing what is needed to run older versions of OS/2 on VirtualBox. The ‘skinny’ is that Microsoft OS/2 is the way to go as they included the 386 method of switching from protected mode to real mode in their product, while 1.0 and 1.1 from IBM relied on the 286 triple fault.
Almost all versions have timing issues however. And again they are covered.
I may finally have that excuse to dig around and install OS/2 1.0!