I don't think it's possible to change a player's level without them being online (besides editing the accounts file, which you can't do via script). I could be wrong, though.
edit: yes, it's possible, see Jer's post below
The typical solution is to have a list of levels where players aren't allowed to log off in, and then warp any players who log in in this levels to OSL.
PHP Code:
// just an example, put this wherever your server handles log-on stuff
function onActionPlayerOnline() {
temp.unstickLevels = {
"era_event-",
"era_spar-"
};
for (temp.unstickLevel : temp.unstickLevels) {
if (player.level.name.starts(temp.unstickLevel)) {
player.setLevel2(...); // send player to OSL
break;
}
}
}