Insert billiplan code in radacct table during authenticaiton

Hi all, I am using freeradius for AAA of my cable users. Now what I want to do is, insert billiplan code 001 into radacct table during authentication so that I can view online users according to billingplan code. There will be Billingplan field in radcheck table and when users tries to login the script will check the radcheck table and update that billingplan code into radacct table. Is it possible with rlm_perl module? Thank you Bishal