You can access the flags/variables in server options on the serverside with the serveroptions. variable prefix.
PHP Code:
temp.staffaccounts = serveroptions.staff.tokenize(",");
if (player.account in temp.staffaccounts) {
echo(player.account SPC "is staff!");
}
I've had issues with just using (player.account in serveroptions.staff) before so that's why I use the tokenize to split it up based on commas.
I personally just have a check in the onActionPlayerOnline, and set client.isStaff true of false depending on the outcome.