Is fully supported by OpenSC. It is tested very often (to be precise: Rainbow iKey 3000 which contains Starcos).
Currently only Starcos SPK 2.3 is tested. If you have a newer version, please report back.
G&D is a very nice company, their APDU manuals are public available, all you need to do is send an email asking for them, and they send you the latest version. This is great! Thanks G&D!