Hi,
I think the best solution in your case, would be to start from DOS not windows 98.
If you want try without breaking anything in your system , you can try from a boot disquette. Do like that :
Find a a DOs version of mame. And install it in : c:\dmame
From win98 , open a dos prompt .
Put a blank floppy disk in your drive
type : Format a: /s
then type :
notepad a:\Autoexec.bat
in the notepad type :
c:
cd \
cd dmame
dmame mspacman
Save and close.
then reboot your PC and boot on A: , it should work.
If you have an arcade monitor (15khz) , you may need to use the ARCMON.SYS driver (it is free).
So , on A: create with the notepad a file called : CONFIG.SYS (or edit the one existing).
add the line :
DEVICE=ARCMON.SYS
Then boot, now it should work with a 15khz screen without the need of an ArcadeVGA
If it works for the floppy. You can then transfert that config to your hardrive.
If you want really stay in win98. Create a .bat file called for instance : mspacman.bat with something like :
c:
cd \
cd mame
mame mspacman
And copy it in the Startup folder of win98.
hoping it helps you.