You can use flashrec to flash the patched recovery, from where you can do all the usual stuff (and even put the old hboot back on if you want!)
flashrec is using an exploit that isn't patched yet in the current kernel used by HTC, however if/when HTC patches this, flashrec will stop working.
So for now it's ok but a next version might have patched this, so keep this in mind !
Thanks for the original headsup by Magnus and Modaco, adapted from here
1. On your phone, goto Settings, Applications, and make sure Unknown source is checked ON.
2. On your phone, goto Settings, SD card and phone storage, and click Unmount SD card.
3. Then click Format SD card (it should automatically remount after this).
4. Plug the phone into the compuer via USB, then pull down the notification bar and click on the SD card notification. Then click mount.
5. Download this APK and recovery image and save it to your computer:
Cyanogen’s / Modaco Hero Recovery Image
Update: updated flashrec here
6. Extract the cm-hero-recovery.img out of the MoDaCoPatchedRecovery-1.0.zip and put it somewhere on your computer.
7. Save both the cm-hero-recovery.img and the flashrec-20090815.apk to your computer, then copy them both to your SD card
(do NOT put them inside any folders on the SD card, just put them in the root of the SD card itself).
8. Unplug the phone from the computer once they are downloaded to the SD card.
9. Goto the Market and download Linda File Manager or any file manager program if you do not already have one.
10. Open the file manager and goto SDCard and then find the flashrec-20090815.apk file and click on it.
If asked, tell it to use Package Installer to open it. It should automatically install the apk.
11. Open the FlashRec program and click on Backup Recovery Image and wait for it to finish.
12. Once done, click on the empty text box in the FlashRec program and type:
Then click on the Flash Custom Recovery Image button and wait for it to finish.
13. Turn off the phone and turn it on into Recovery mode by holding down Home and Power to turn it on
(keep holding until the recovery screen comes up has a bunch of text on a black background).
As long as that screen comes up, you have done it correctly and can now go and load other ROM/hboot/whatever.