ipv6 link local default route

Hi,

Probably I am misreading the route man page, but I would like to give my 
box a link local address as the default gateway and for that of course I 
need to specify the interface (the link).

I suspect the -link modifyer to accomplish this, however, where do I get 
the required numeric specification for a particular interface?

I've tried guessing, but no chance:

# route -6 add -link 1 default fe80::1
add net 1: gateway default fib 0: Address family not supported by 
protocol family

Thanks

Ede