N64 S-Video Restore Install Guide
This guide will help you to install the N64 S-Video Restore flexcable.
First disassemble your N64 console until Step 7 and remove the board: Ifixit Guide.

Cut 2 traces on the back side of your N64 near the Multi-Out.

Solder the flex to the MAV-NUS Chip

Flip the flex to the other side and solder it to the Multi-Out.

When readding the shields make sure the flex bends acording to the image.