Anders,
I'm really sorry but I'm not familiar with Unicable and how it relates to DBS Bandstacking. For North America, DBS Bandstacking is "simply" adjusting tuning frequencies so it was easy to implement but it looks like Unicable is a bit more complicated (i.e. it appears to send different DiSEqC commands and a lot of other differences).
I think to get this properly supported we would need a developer with access to a Unicable system. I wouldn't be able to do this myself but if somebody wanted to give it a try I would definitely help in any way possible ...