1. Navigate to wherever you have Tony Hawk's Pro Skater 1+2 installed and go to it's Paks folder
Example: D:\TonyHawksProSkater\Base\Content\Paks
2. If it doesn't exist, make a new folder called ~mods - Should look like this: D:\TonyHawksProSkater\Base\Content\Paks\~mods
3. Drop the mod's pak (pakchunk0-DodylectableModificationsGHWTDENeonDeck_99_P) in there
4. Boot up the game and equip the Fuming Snot Snake deck design (It costs $100 in the Skater Shop if you don't have it already)
Have fun!