Thanks for all the replies guys, I'm thinking I'll try CranActin. Also I'm gonna take lots of water and creatine, along with vitamins. Hope it works!
Getting someone else's clean urine is the best way to go. Not everyone has this option or is comfortable with it.
Diluting won't be too hard if you aren't a chronic smoker (I get the idea that you're not). And if you don't smoke between now and your test in a few days, you should be
golden.
Tutorials abound online on how to doctor your urine, so check around if you don't find the information you need here.
Supplement with creatine now until your test. The day of your test, DRINK WATER ALL DAY. As in, wake up early, DRINK A TALL GLASS OF WATER, eat some breakfast, MOAR WATER, take a shower, MOAR WATER.
Seriously, before you get to the test center you should have urinated several times already. Take your B-complex 1-2 hours before test time, and be sure you take about 500% the daily dosage.
The highest concentration of metabolites will be in your first pee of the day. While peeing, the beginning and end of your stream will also contain higher concentrations. Don't begin collecting their specimen until you've begun peeing already (even 1-2 seconds is enough).
Don't break a sweat. I've done this several times before. Worst case scenario is they tell you to retake because it was too dilute.