You can find this by typing "slow computer down for old games -cpukiller" into google:
http://moslo.info/moslo.asp
(as recommended by Apogee)
Get the Windows one. In dosbox you can just change cpu cycles.
It's better than cpukiller, imo, though I've never had that lock up.
[ed]
but i don't see the problem with running this in dosbox...