Update...well I finally did it. It didn't take any particular tricks, just some good driving and a bit of luck. If any one else has trouble with this one or evading any pursuit for that matter here are a few tips that might help:
1. If the Heat is above level 4 hit the pursuit breakers as often as you can and disable as many vehicles you can. If you can knock down the pursuing vehicles to one you will buy yourself 30 secs to 1.5 minutes to evade or just calm the nerves.
2. When doing a timed pursuit as in the challenges try to stay near a hiding spot towards the time limit. I believe I evaded the pursuit within 30 secs of the 12:00 Min mark.
3. When you need to evade the police for long periods of time stay on straight non curvy roads, use the speed breaker at all road blocks, and never use the back button to reset your car. I think everyone knows that last one but it is always good to remind you now and then.