I applied last year but got turned down. App process is easy enough and you need about 3 referees. Another requirement was that you had to have been to the magistrates court at least twice and sat in on proceedings prior to the interview.
The interview panel consisted of 3 people. 2 magistrates and one non magistrate. The explanation given for this was that it was to stop magistrates recruiting clones of themselves.
I would have applied to Chichester, but they weren't recruiting at the time, so I applied to Portsmouth instead. I can't say I was all that disappointed at not being selected on the basis that their loss was greater than mine. You don't get paid, whereas a Judge doing the same thing earns over 50k.
More general info at
http://www.direct.gov.uk/en/HomeAndCommunity/Gettinginvolvedinyourcommunity/Volunteering/DG_195543