I have yet to install any custom ROMs on my device, but I have looked into it enough to say I am 95% sure I coud do it.
The fact that adb devices doesn't return any connected devices suggests that you haven't properly rooted your Hero. Try reflashing the custom recovery image. Check out this page:
[GSM/CDMA] 09/11 - Installing the patched recovery image on your device - Android @ MoDaCo
It has the easiest method of rooting your phone and flashing the custom boot loader.