I guess the entering should be enabled for people with 3- stars. When entering the 'carshow safezone' they would get a bribe offer from server. If they don't accept it in 30 seconds they should be slapped(with 200hp) automatically after that period and of course jailed after death. Other wanted criminals with 3+ stars wouldn't be able to get in the area, something like new CnR system disallowing criminals to enter after the event started.
To prevent criminals killing someone within those 30 seconds, weapons should be disabled in the area and also as it is safezone cops wouldn't get damage from snipers around.
Criminals would accept server bribe with: /acceptsb (Or anything other, just came up with this).
If a criminal gets arrested in those 30 seconds, he could accept the bribe and be instantly released as in normal script. But if we disable weapons then lets disable nightsticks too.