IIRC, EmuTOS is based on the sources for DRI GEM that were open sourced awhile back. The actual GEM sources might be a good starting point for building a VDI driver.
Admittedly a 020 introduces new complexities. Part of why in my own 68K design I plan to use the only 68K cpu more odd than the 68008, the 68012. Its essentially a 68010 with two 30-bit flat address ranges.