I'm assuming you've installed the php module under IIS?
If so, what's the problem?? Just edit your IIS config to send asp pages through the PHP parser. Therefore, in theory, the asp should be executed as well as the php...
...shouldn't it???
Being a rescued former microsoft slave, i now use a linux based server with apache so I am not 100% sure about this fact.
Anyway, if you have any joy, please let me know.
Cheers.