Run something in the background in VPC to keep W98 a bit busy, music or something... But chances are your game will become a bit jerky,trial and error......
Or use one of the older CPU killer progs that run in W98. Most of them can be set to use a % of the CPU.
[Edit]
One of many:
http://www.downloadatoz.com/utility_...ory/cpukiller/
For good understanding:
Run it
IN VPC.