Hi Joe,
No you cannot do that ... the WAAS is not a firewall ;-)
take a look here, what you can use IP ACL for :
http://www.cisco.com/c/en/us/td/docs/app_ntwk_services/waas/waas/v531/configuration/guide/cnfg/ipacl.html#wp1054042
Basically you can use it for :
1) controlling (management) access to the WAAS itself
2) excluding traffic from being optimised, but suggest that you use policies instead
in WCCP mode, you cannot do it on the WAAS either, but will have to do it on the router.
Best Regards
Finn Poulsen