> ... I have no patches, they're all the same
> sound, but that's OK. I don't have a USB-to-midi device...

The other approach (without using MIDI) is to use the .wav versions of
the patches from the site
(http://www.rhodeschroma.com/?id=polarispatches).

You can then feed the audio-out from your computer into the Polaris, and
then generally follow the 'loading from cassette' instructions for the
Polaris.

(Note - if you don't have the DIN connector cassette cable, you can
instead use the SYNC IN 1/4" jack input on the Polaris, as it also
connects to the cassette data in).