How to disable text chat in Source engine games

The server alias syntax is the same as on the client side. You can place aliases inside server.cfg or choose to separate them into their own file for the sake of neatness.

server.cfg

exec aliases.cfg

aliases.cfg

alias "meleeon" "sm_cvar sm_meleemode_enabled 1;sm_cvar example 0"
alias "meleeoff" "sm_cvar sm_meleemode_enabled 0;sm_cvar example 1"

You should also be able to change the default values of cvars registered in SourceMod plugins or have them vary by map. Just ask if that interests you.

autoexec.cfg is automatically executed once when the server starts before a map loads

server.cfg is automatically executed each time a map loads, including map changes

There's also map specific configs that are named after the map. These are executed last.

You usually want to put all of your server configuration in server.cfg so that any setting changes, such as from a mapname.cfg file, are reset when the map changes. The autoexec.cfg is used for anything that should be done before a map loads, such as sv_pure settings.

Also, you can change which file is executed on map change using the servercfgfile cvar. This is handy if you want to have different modes on a server, or run multiple servers from the same installation.