Flexfields for Ebtax?

 We are going to start using a third party vendor for our taxation purposes.  Since we will be keeping track of our registrations and exemption certificates in this other software app, we were looking for places to bring information back from our application into Oracle ebtax.

It appears that in the zx_lines table there are some attribute fields which makes me wonder if we couldn't set up some descriptive flexfields to hold certain pieces of information such as the registration #'s, messaging, etc for our invoices?