First off you need to know what chipset your wireless card is. Atheros or Prism2.5 is ideal, but Ralink will work too. Otherwise you're SOL. Also a working Linux harddrive install would probaly be good. LiveCDs are okay, but don't allow for driver patching.
After that I suggest checking out http://aircrack-ng.org . They have some driver patches that will make your process a whole lot easier.
After you get your drivers patched and whatnot, it's a simple process of downloading the aircrack-ng sources, making them, then messing around with aireplay-ng till you get injection working