The following information has been taken from AstronomyForum.net:
Update August 2009 - most recent firmware V3.25
What you need:
2) EQ5/HEQ5/EQ6/HEQ5 PRO/EQ6 PRO/EQ5 PRO/Atlas/Sirius
3) RS-232 serial to USB cable
5) firmware loader
Make sure you check what version you are running now. When you turn on your handset what does it say:
Also make sure you know the difference between AZ (alt-azimuth) mount and EQ (equatorial mount). This will help in either picking the newest download (3.07 for AZ, and 3.25 for EQ).
If you have AZ, download the 3.07 AZ firmware!
If you have EQ, download the 3.25 EQ firmware!
The newest for AZ is 3.07 here:
For EQ, the newest is Firmware 3.25 Download:
You need for either AZ or EQ, the software loader here:
Firmware Loader (you need this to upload new firmware to handset):
Connection detection utility (will detect if there is a connection from your computer to the handset):