networking - IPv6 and IPv4 mapped address

I've a box with 1 private IPv4 (192.168.0.X) and some IPv6 (let's call one Y::Z).
I have an application listening on 192.168.0.X on port 1234 and an application that want to connect to that service but use Y::Z as source address.

So I thought about using ::ffff:0:0/96 prefix but telnetting ::ffff:192.168.0.X (using source address Y::Z) give me a "network unreachable" error.
I've tried to add routing rules but seems that nothing works.

How I can allow

 telnet -b Y::Z ::ffff:192.168.0.X 1234

to work?

Thanks.

edit:
OS: Debian Squeeze (in an OpenVZ container, kernel 2.6.32).

I also forgot to mention that

 telnet -6 ::ffff:192.168.0.X 1234

works without any error.