I just flash my Acer A500 with Acer_AV041_A500_0.019.00_WW_GEN1
This method works with my. I can use titanium backup and superuser. Thank you!
But I don't know how to test push a recovery image.

below is my way to root.
I use windows Vista.
1. On a tablet: "Settings" -> "Development" -> "USB debugging" switch on.
2. Сonnect the tablet to the computer.
3. Unpack the files. then put ICS_rooting folder in c:\ (I try unpack in other place not work)
4. then run runit-win.bat by run as adminstrator.
Done