This method may or may not work for you. I take NO CREDIT for making this happen, I'm just writing a quick howto. Thanks to strra for making it convenient.
Typically, attempting to boot into Recovery would generate an error that recovery image was not verified (something along those lines).
Thanks for all the devs who made this possible - you guys are amazing. Donate to them if you can, they deserve it.
If you don't feel comfortable with this possibility, stop here.
Install the A500 drivers from Acer on PC (from Acer's site).
Install and launch Android terminal app on tablet. Run the following command:
Use Vache's site to convert that number into your SBK (four long hex values).
Extract all of the required files (batch.rar and nvflash) from strra's post into c:\nvflash.
Open up a Windows command prompt (cmd.exe) and then `cd c:\nvflash`.
Launch `run.bat`, but don't enter your SBK yet.
Power down the tablet.
Use a paper clip and hold down the Reset button. Do not release it. Hold down power for 3 secs and then release it. After another second, remove the paper clip. Your Windows PC should then detect your device and install the APX driver. You should then have an APX USB device installed. If you do not have an APX USB device listed in your system tray, you cannot proceed.
Go back to the Windows command prompt and enter your SBK. Once you enter it, the process should begin. If you receive a USB write error, your SBK is incorrect.
Once the process begins, the Windows command prompt will read "Press any key when your A500 is in bootloader mode". Do not continue until the tablet is in Download Mode.
Once the tablet reads "download mode" (something along those lines), you are in bootloader mode. You can proceed and it will begin formatting the various partitions and installing the recovery.
Once the process completes, it should say PASS. You can then power off the tablet and power it back on again.
Make sure your tablet boots.
Power the tablet down and attempt to launch CWM via Power+VolDown.
Remount /system rw:
su mount -o remount,rw -t ext4 /dev/block/mmcblk0p3 /system