You can get the iBill manuals from
http://www.ibill.com/support
I've been going over them recently. I wish those fuckers would send me the damn password script I've been requesting since before Christmas. So much for "premium" support. Also, their Direct Integration testbed is down. I guess these are the least of the issues people have been having with them.
Anyway, iBill product codes are always in the form XXXXXYYY where the X's are the company code and YYY is the individual product code, ie, 100. is that what you wanted?