Definitely on the right track. A housing, DI cartridge, some tubing and a John Guest tee should do it. Try to get a refillable DI filter, it will be a little more cost effective than the throw aways since you'll be able to buy the DI beads in bulk.
http://www.buckeyefieldsupply.com/sh...ory=39&Sub=127
http://bwiplumbing.com/ca/index.php/...cartridge.html