Hi,
I guess without resorting to somekind of playing around with NAT then the only option would be to configure the ASA in Multiple Context Mode and separate the 2 Vlans to each use their own Security Context.
To be honest, I have thought about opening a TAC case about a NAT setup that according to the Cisco documentation should enable using NAT to determine the eggress interface for certain traffic. However currently the ASA seems to always do a route lookup anyway.
- Jouni