I believe you have to ivoke Weaksoft key editor.
Follow the route [ Menu Key -> Installation -> (Enter your securuty code, by default 0000) -> System Set-Up -> System Information ] such that the firmware version is shown.
Remaining there please Press the following keys in sequence
1. KEY_4
2. KEY_2
3. KEY_2
3. KEY_5.
So the sequence "4225" will invoke the WeakSoft Editor for further use.