I've just flashed a CyanogenMod 9 (Ice Cream Sandwitch) onto my HTC Hero and it's pretty cool but it doesn't connect to an ad-hoc wifi spot. There is a good old flashable piece of software somewhere in xda-developers forums but you just can't flash it using the current ClockworkMod Recovery (using any 3+ CWM recovery version, actually). It says something like:
Amend scripting (update-script) is no longer supported. Amend scripting is deprecated by Google in Android 1.5. It was necessary to remove it when upgrading to the ClockworkMod 3.0 Gingerbread based recovery.Please switch to Edify scripting (updater-script and update-binary) to create working update zip packages. Installation aborted.That means you need CWM recovery 2.x to flash the ad-hoc support hack.
The easiest solution is to install the Rom Manager from the market and flash the recovery from it. It'll flash 2.x.x CWM Recovery onto your HTC Hero (I assume it flashes the last version CWM guys support for our dinosaurous devices). Now you can reboot into the recovery mode and flash the ad-hoc support piece. After that you are safe to flash cwm recovery 5.x again.
Now you have an ICS CM9 device able to connect to ad-hoc networks.
Cheers,
Zoreg