Not to bash this guys stuff....well maybe I am gonna bash it a little. (And I'm not bashing you Jas, I'm bashing the fastfuel folks).
Begin rant...
Think about this.
You put oil in it. It's waste oil, it's got a lot of junk in there, right? It's gotta go SOMEWHERE. Where's that? (maybe the filter). How long's it gonna take to clog that teeny weeny filter? (about 2 gallons). That's assuming it's actually rated at what they claim.
Also, can you image filling your truck with a SPOT SPRAYER? It would take FOREVER to fill up. I'm using a 1" pump rated at 720 GPH and it still takes a long time. Oils are HEAVY, and it'll tax any pump you're gonna use.
Rant over....
Here's what I'd do. Run over to biodiesel.infopop.cc, take a look at the SVO forums. Lots of good reading from folks that have done it before and will FREELY show you how to do it.
Also -- if you're stuck on the spot-spayer idea, I'd get a few bag filters from McMaster-Carr (get a 1 micron final filter), and just run it through there. I got a 4"x8" 1 micron for $3.82 last week. You can rig up some PVC fittings to make a housing for the filters...