I recently bought a Trio Stealth Pro 7c, which uses the Allwinner a13 chip. In order to flash a rom, you must use LiveSuit, which is a Chinese-made, Windows-only program. You boot your tablet into recovery mode, and LiveSuit will flash the rom you provide.
The rom must be in a specific format, so if you want to create a custom rom to distribute, you have to go through a lot of steps. For more details see this forum or this post*.
There are a number of pre-built roms for A10, but A13 roms are more difficult to find (if only for the fact that most people don't realize there is a difference).
You can install ClockWorkMod on your tablet, if you want, but you probably won't be using it to flash roms. I did, but I am still unable to simply flash a rom properly. You can still to full nandroid backup and restores.
*Full disclosure: I wrote this post. Actually, your question caused me to finish my rough draft and post the finalized version.