My preferred method would actually be much simpler :P
As with many games, GTA: SA will recreate its registry settings if it is copied from PC to PC (Have tried this!). Therefore, I would just use WinRar to compress & split the image into 700mb chunks (It's one of the Winrar spanning presets) & burn these to CDs. When you want to reinstall, simply open the first of the spanned files, and then insert a new CD when it asks for the next part.
Simple
-Leezer-