[otrs] How to self generate Customer ID from Customer tab in Agent interface?

Hi, I want to generate Customer ID automatically from the OTRS Software, not manually, in a particular format like[b] ABCD/0001/11-12[/b] and the next time it should generate to [b]ABCD/0002/11-12[/b], here 11-12 denotes the year, after completion of 2011 year, the format should change to [b]ABCD/000199/12-13[/b], please guide how can i achieve this, looking forward for your kind reply.