exec("Add-Ons/AddOnCat_AddOnName/server.cs");
Like that. Or if you don't want to put a bunch of execs in one file, try this:
function execFolder(%filepath) {
for(%file = findfirstfile(%filepath @ "/*.cs"); %file !$= ""; %file = findnextfile(%filepath @ "/*.cs"))
exec(%file);
}
And use execFolder("Bricks");