Installation Captive Portal

[vicissu]

Hi, my name is Vinicius!
I have a big problem with our friend Captive Portal!
I have it installed with squid and squidguard.
I use the voucher system in a public network where users request the keys!
How can I generate a decent log of these vouchers so you can protect my institution of any audits in the future?
More technically speaking, how can I generate logs in lighsquid that instead of appearing oo Ip appear vouchers?

Sorry for english, I'm from Brazil! kkk

thnks