There is no point in porting a hero ROM. It wouldn't help making the ROMs.
To install it, it is quite simple.
Go to the thread
http://forum.xda-developers.com/showthread.php?t=716282
download the tools from point 1.3 and the new SU from the bottom of the post.
run adb (explained in 1.1) and execute the commands from 1.5.
execute the commands from 2.3. Standard, you got the Amon Ra recovery in the tools you've downloaded. If you need another one (like clockworkmod, needed for the experimental gingerbread rom, you can just replace it)
Then your tattoo is rooted and you can flash a ROM to it. Check this video about how to do it.
http://theunlockr.com/2010/03/30/how-to-load-a-custom-rom-on-the-htc-tattoo/
Note that, depending on your machine, you need to use the volume buttons to go up/down and the green phone to select (as shown in the video) or you need to use the arrows to go up/down and the dpad to select (as I had to do with my phone).
hope it helped.
I currently use Kalim's ROM:
http://forum.xda-developers.com/showthread.php?t=872668 . It is very stable and the camera is under way. I think he will get the camera fixed within about 2 weeks or a month.
To update a ROM, you don't have to do the wipe step from the video.