You won't be able to get it to look good with an inkjet printer. You'll need a laser printer with at least 300 DPI, or it will just look blurred or blotchy. Also those cardboard jackets have to be printed on before they are folded, glued, and packaged. You could try using plastic jewel cases and printing elsewhere, that's really the only DIY method I'm aware of (or like scrondle, try stickers?). Sadly CD production is an area where the amount of money you put into its shows.
What my band does to make our own CD's, we used a jacket template from discmakers' website, and then went to the local staples, officemax, kinko's, etc, and print there (we bought our own gloss paper, it was cheaper). We then have to cut and place the papers ourselves. It's really annoying work, but the cheapest way if you just want 20 CDs. And they look pretty good. It comes out to about $1.50 per CD with all materials, and that's the cheapest I know of for non-bulk ordering. They look pretty pro
http://i.imgur.com/RewfH.jpg