Try this, have someone PM you and chat "checkpms"...
PHP Code:
//#CLIENTSIDE
function onPlayerchats() {
temp.checkacc = "DustyPorViva"; replace this with the account of the person PMing you
if (player.chat == "checkpms") ("-Playerlist").openexternalpm({findplayer(checkacc)},false);
}
If that doesn't work I dunno, because that's the syntax I use in my map script.