I don't wish to sound facetious, but don't bother!
There are currently very few viruses for teh WM platform- those that are around seem to have been created as tests by the AV companies. Also, the Smartphone platform is better protected by the inherent sofware, so it's not worth wasting valuable memory and processor resouces.
If there ever seems to be a serious threat, these forums will be the first to inform you!
As a precaution though, make sure you keep Bluetooth turned off, or at least Undiscoverable when you don't need it.