Joomla Gurus--I need help with JACL and AD

I have a Joomla set up with JACL and LDAP. What I want to do is:
1. Create groups in JACL that are named the same as groups in AD.
2. Check the following when someone accesses content:
a) Determine which AD groups they are members of
b) Check if any of these AD groups have a JACL group
c) If so, update the $my->jaclplus to contain the merged access values

I've figured out how to determine the groups on AD, but I don't have a clue
about updating the $my->jaclplus value for the current session. I don't
necessarily want to change the DB values since users will change group
membership, but if updating the DB is a better solution I am open to that as
well.

Ideas? Questions? Help!

Thanks,

-Mark