1. Activate ISG
2. Enter the File
3. Enter Japes, Tag Diddy, and enter the underground.
4. Enter the cannon to cancel 1:26 Fadeout.
5. Enter the mountain.
6. slam the switch at 2:33 so that the cutscene will be stored when that cutscene fadeout when you'll fade into intro story.
After that you beat krool to get back to dktv to activate the japes mountain gb spawn cutscene, and you'll be in japes mountain with diddy, eventually he will hit the void trigger and have lanky in training grounds.