WMR89 on MAC

After much mucking around i got my wmr89 working on windows but ideally i want to have it working on my mac. After a lot of searching i have drawn a blank on getting it going on the mac. It all comes down to the comport i think. I can choose the comport in the widows version of WD but no comports appear in the mac version. So what am I missing?

The problem is there is no osx driver ( virtual USB to serial)

Thats ok. Im using my weatherundergroud data at the moment