Is your proxy server capable of doing WCCP ?
If so you could use WCCP on the router subinterfaces for vlan 2 and 3 and redirect traffic that way.
The other solution would be to try PBR and redirect traffic to the proxy server that way.
Either way a couple of questions about your diagram -
1) are you really using those IPs internally ie. they are all public IPs so unless you own them you must be doing NAT on your router ?
2) your subinterface configurations are for the same vlan and all are marked as native. I suspect this is a typo but can you clarify ?
Jon