dyndns update with routing marks

Is it possible to let your Mikrotik router v5.20, be able to update your dyndns account with a gateway that has got a routing mark,

Ive got 3 Wan links on 1 router, with routing marks for different subnets, now I need 1 of those lines to update a dyndns account for me.

I tried the scripts, but I dont know anything about scripting

Thanks