I would advise not to use Fun module: set_user_hitzones
It would be best if you used FakeMeta and hook TraceLine at post stage, search the forums how to do this.
The reason it's not advisable for using Fun is due to the way MetaMod works, it fails to copy the altered pointer data to proceeding modules/plugins. So if you had a plugin which is using set_user_hitzones and another plugin which is loaded afterwards using FakeMeta (TraceLine) for example your plugin will fail to alter the hitzones correctly.