Here's the link on rolling fenders, courtesy of Luke@TireRack:
http://www.andrews.edu/~johnsonm/howto/rollfender.html
You know, this is the third time I've copied and pasted this link in the past week. At least it was easy to find...
Of course, you can - and perhaps should - have a professional do the job, but it can run over $200. And no, they don't use a baseball bat - there's a specific tool for the job.
If you do the job yourself, you might want a second pair of hands to aim a hair dryer or heat gun - on low - at your paint to keep it from cracking.