It can't be as far as I know. here you are the script, I'm not quite sure about et_InitGame and restart eq 1 if it is a call before or after map_restart.
maps = { "adlernest", "fueldump", "goldrush" } -- add map here
command = "!crazygravity" -- command here
function et_InitGame( levelTime, randomSeed, restart )
if restart == 1 then -- not quite sure
local i = 1
while maps[i] ~= nil do
if tostring(et.trap_Cvar_Get("mapname")) == maps[i] then
et.trap_SendConsoleCommand(et.EXEC_APPEND, string.format("%s\n", command))
break
end
i = i + 1
end
end
end