Your NAC appliance and the software running on it are end of sales now for a long time.
http://www.cisco.com/c/en/us/products/collateral/routers/7600-series-routers/eos-eol-notice-c51-734104.html
Cisco is no longer updating the software and as such there is no work around for the SWEET32 vulnerability. There is a bug ID confirming this fact:
https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvb48635
The SSLv3 issue similarly has no fix on the NAC product.
You can replace the self-signed certificate for that one bit; but overall your organization should move off of this outmoded solution to something like Cisco ISE for network access control
