What i did to get A2SD was go to
14/Jun r6 riskfreeroot - HTC Desire rooting guide - now with HBOOT 0.80 and OS to 1.21 support - Android @ MoDaCo to root the phone in the first place - which is what you've done.
Then Lekky's guide won't work for us as we have 0.80 bootloader. So dont use that - i tried 3 times!
Once its rooted as above, go to here:
10/June v1.8.1.7 - fake-flash by Koush, launching recovery on your device without a PC - Android @ MoDaCo and make sure you can access the Custom Recovery screen.
If i remember correctly, the second step of that says to put update.zip onto your SD card but from the download on that page there isn't one! Anyway, what you had to do was just rename the zip you download to update.zip ... something that took me a while to work out!
Anyway, you are ready to move on once you can see the NANROID BACKUP option in the green menu following these instructions.
Then i went here:
27/May r3.1 - MoDaCo Custom ROM for HTC Desire with Online Kitchen - Android @ MoDaCo and choose the option called "-
r3.1 ROM with default MoDaCo additions and A2SD+" with this link:
http://coblitz.codeen.org/www.romra...odacocustomrom-withadditions-a2sd+-signed.zip
This is a Modaco homebrew ROM, so i am a free member there and as you can see it includes A2SD+ (which is same thing)
Now with that zip also on your SD card go to the NANDROID BACKUP found in the CRI (Fake-Flash) section and after selecting NANDROID BACKUP it will then ask you to update from SD and you select the Modaco 3.1 zip!
Good luck