Hi Casey,
I guess read the BAT file and see what it uses. Also I guess the "path" to OpenSSL exe might be important. (Its been a long time since I last read the BAT file, so I don't have the details to memory.)
Frankly, you'd be better off generating the CSR for them. It doesn't sound like they're gonna be able to do it properly themselves. Or use a provider that has an online generator.
cheers
Bruce