haynes do quiet a good book on engine manigment writen by dave walker of emreld ecu's and ppc mag fame covers efi and ign setup.
no idea about megajolt but megasquirt and meny other aftermarket have a thing called a spark table or ve table
basicly its a graph or ref table with load and rpm on the sides and timing value in the intersection of the two values.
we ignite the mixture befoe tdc (+tdc) and ajust the amount of advance with load and rpm
the amout we want/need verys on temp air and engine,compression ratio, boost,fuel octane rating and the list go's on so two engine maps may not match unless you have exactly the same engine
no damage is done by over retarded ign but is if over advanced (adv) so we start by increasing adv to a sweet spot (best power and cleaner burn) if we advance beyond this point pinking or knock stars and if we advance some more detionation (clap of two pressure waves in cyl) this is where a hot spot melts holes in engine bits
you have possible herd pinking before when you load your car engine pulling out of a juntion with the revs to low and to little clutch or put some 2star in your tank when your car likes 4star (yester year) it sounds a little diesely or like a load of little hammers in your engine
detenition it simmular but louder and naster
so start low and advance until you get pinking then retard it a bit for each load/rpm site basicly