Might be a solution for those whose BIOS is unfixable (with the limitation that fullscreen may be broken), but I agree that fixing the BIOS either with 32bit I/O fix or by patching problematic functions is a better solution.
Regarding the symbols for NTVDM.EXE: You can get them from the Microsoft Symbol Server. You can set up your favourite debugger to use them.
i.e. in Windbg, you can either enter Symbol server path in menu or just start windbg with:
Code:
windbg -kl -y SRV*C:\temp\*http://msdl.microsoft.com/download/symbols
Where C:\TEMP is a valid path to cache symbol information. Some of my patches rely on these symbols too in order to find the correct location to patch within the NTVDM.EXE of the user's version. With the increasing number of versions released, hardcoding these offsets per build-number doesn't make a lot of sense anymore, as they are constantly changing.
OllyDbg, x32dbg and alle the other nice debuggers that are good for patching executables support symbol server too.