Here are the steps I performed on the Telstra A8183 Desire (Note: I am using it on the Telecom New Zealand XT Network)

• If not already done, Install HTC Sync and restart your computer (Yes you actually do have to restart or it wont work)
• Format the microSD card to FAT32 format (quick format is OK).
• Put the microSD card in your device and boot it.
• Launch GoldCard Tool (Right Click and run as Admin if needed)
• Connect Android device to USB and enable USB Debugging (Settings --> Applications --> Developer --> Enable USB Debugging)
• Click 'Get CID' (If MMC1 fails try MMC0)
• Navigate to http://psas.revskills.de/?q=goldcard, enter the CID number from Goldcard Tool and create your Goldcard image, which will be e-mailed to you.
• Enable USB Mass Storage on the Desire if its not on already
• Click 'Refresh' and select your microSD card in the drop down menu.
• Click 'Load GoldCard.img' and open the .img file you got by email.
• Click 'Patch MMC'
• Download and run RUU_Bravo_HTC_WWE_1.21.405.2_Radio_32.36.00.28U_4. 06.00.02_2_release_126984_signed.exe
• Once the phone is flashed, download OTA_Bravo_Froyo_HTC_WWE_2.09.405.8-1.21.405.2_release4dua3bcrut4wrv30.zip and rename it to update.zip
• Copy it to your Goldcard and power off the phone
• Turn on the phone by pressing the Down arrow Key and the Power Button This will take you to a menu. Using the volume down button to select recovery mode and press the power button.
• When you see the image of the phone with an Exclamation mark press the volume up and the power button and select install the contents from update.zip