Freenet6 default route

Hi!

I have installed Freenet6 package on my Debian box
and now I have two IPv6 addresses for my box. One
is an address of my side of a tunnel and the other
one is that I got when I registered with Freenet6.

So the eth0 has nice, registered IP and sit1 has
ugly, long IP. The problem I have is that default
IP is this ugly, long one. For example Mozilla
uses it. So how can I set Linux so that it
would use nicer IP (that IP works because I tested
it with programs that support setting source address).

I have tryed setting the route table but I have not any success.

Please help


Mike