Martin,
I tried the vbesvga.drv driver on a bare metal machine booting CSM (BIOS). It works in Win-OS/2 full screen and DOS full screen; the mouse pointer seems slightly less jumpy than when running "normal" Win-OS/2 full screen session. Neither the VBESVGA.DRV nor the "normal" driver will run seamless Win-OS/2 or seamless DOS sessions.