Rename your existing gephyrophobia.map file as gephyrophobia.original
Place the modded gephyrophobia map into your Halo map folder.
Apply the PredV3bits.PPF to the BITMAPS.MAP file in your halo map folder.

You must play the mod on CTF, (theres only one player spawn point)
preferably spawning on red team.

Hint* many of the weapons can launch grenades off right click. 
you can access the sniping platform in the centre of the jungles, by going through blue base.....