Sales Commissions Upload


I need help on Sales commissions setup. We want to setup sales commissions to a group of sales reps based on Order Address Zip codes (entered manually in SO - don't have an address book record). Looks like this cannot be achieved in JDE.

So, I thought I will setup the sales rep commissions groups based on Item Cat codes and then writing a UBE that reads the Zip Codes from F4006 and Item Cat codes and writes commissions in SO Header and detail commissions tables directly (F42150, F42160). If I do this, will the commissions be applied like the normal process? Any ideas (or) suggestions will be greatly appreciated.
Thank you.