Hi,
Check this URL for more details on how WCCP works.
http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/fun_c/fcprt3/fcd305.htm#1000909
The following sequence of events details how WCCPv2 configuration works:
1. Each cache engine is configured with a list of routers.
2. Each cache engine announces its presence and a list of all routers with which it has established communications. The routers reply with their view (list) of cache engines in the group.
3. Once the view is consistent across all cache engines in the cluster, one cache engine is designated as the lead and sets the policy that the routers need to deploy in redirecting packets
As stated in the document, you need to configure the inside ip address of your pix firewall in the bluecoat cache device.
To use WCCP in pix, we need to follow the guideline recommended by cisco.
As far as i know, there is no workaround available to break the way WCCP is implemented in PIX.
Hope this helps.
-VJ