Meditation can definitely be helpful in recovery--at the very least, it can cut down on stress and help you to settle down after overstimulation. But it takes a lot of time, patience, and effort to get good at it.
As for relieving your anxiety, don't expect meditation to work any wonders. It sounds like you have an anxiety disorder--possibly OCD--and while meditation is an important part of dealing with any anxiety disorder, it is very unlikely that you will be able to manage such a disorder with meditation alone.
Are you getting any treatment for your anxiety? Are you on any medications? Have you tried Cognitive Behavioral Therapy and Exposure/Response Prevention? These are the most effective treatments for OCD, bar none...and they can be effective with other anxiety disorders as well.
If you're able to get some treatment for your anxiety, then meditation would be an excellent way to supplement that treatment. But it's not a substitute for treatment. So, if you go into meditation hoping that it will help you to cope with and manage your PCS better, that would be a realistic attitude. If you go into it hoping to completely get rid of your anxiety, that would be an unrealistic attitude.
Male, 39 years old, suffering from PCS as a result of being rear-ended on 1/23/11. Part-time philosophy professor.