I aren't too genned up on the Megajolt and MegaSquirt systems, all I know is that they are mappable systems you can build up really cheaply and people all over the net are now using them, here is a link to some Megasquirt info

www.bgsoflex/megasquirt.html

But I aren't sure if MegaSquirt can just be used for ignition, it's designed to do it all.