The whole project kind of evolved from the initial idea of making something "awesome". A main catalyst were some favourite sayings of the intended recipient. In addition to the "no kill switch on awesome", he was fond of "Me want cookie" (to counter-act sleepiness in review meetings), "Next slide", and "2013 is the year of the bow tie!".
No one really needs an excuse to add EL wire to a project, and putting things on the jacket to reflect that project we were working on was a no-brainer.
I split the project into two parts, hardware and software, with a partner (Nick Wells) taking care of the software. He actually used the sound and EL sequencer systems to trick out a gingerbread house at Christmas as part of a family contest they have every year, so it made sense for him to carry on with that part of things.
It probably took 20 hours total, but mostly because we worked only sporadically on it.
Sorry there are no schematics, but it's all very simple except the LM386, and there is the National (TI) app note for that in its datasheet. Just be sure to plan out what Arduino IO is used for what and try and keep connections close to the IO pins needed. For example, it's no fun running a wire from one end of the prototyping shield to the DIN connector. A BOM is included in the links section, except for the jacket, which was sourced on eBay from Hong Kong.
Pretty easy project in terms of programming and assembly, though labour intensive in terms of sewing.