Adding a New Diagram type

[Arigead <arigead gmail com>]

Hello all,
    I'm new here and haven't lurked, as yet, but wanted to ask a question 
about adding a new diagram type to Dia. I'm not sure where to start but wanted 
to make structured diagrams like an electronic schematic where the 
interconnections are significant.

I assume I have to add a new plugin? and add my XML components. 

If anybody could point me in the right direction I'd be very grateful.