1. Compute your 6to4 IPv6 address (2002:uuuu:vvvv::1) from your IPv4 address (a.b.c.d):

   printf "2002:%02x%02x:%02x%02x::1\n" a b c d

2. Add a SIT (IPv6-in-IPv4) interface in /etc/network/interfaces:

   auto sit0
   
   iface sit0 inet6 static
   
           address 2002:uuuu:vvvv::1
   
           netmask 64
   
           gateway ::192.88.99.1

3. ifup sit0

Now you can also add AAAA DNS records with 2002:uuuu:vvvv::1 for your domain(s).