tutorial/explanation: completely custom markers for gmap (change all names/icons)??

so i've got everything working, including taxonomy markers and all of that and now i want to do one BIG thing: replace every single marker and insert a new set of my own, smaller and with titles that are very self-explanatory.

this is for a town site, so there will be schools, police, town buildings, etc - so where user can select icon i'd like them to see titles like:

school
town building
emergency

instead of:

blue
yellow
etc

if i create all of the icons as tiny png files (16k or smaller), how do i replace the entire markers file and associated .ini files? has anybody done this - and would you be willing to provide a simple walk through for D6???