To enable TAS Mode, there are a few steps you'll need to take, which are clearly marked. You will need your own wire (28 or 30AWG preferred, as thicker wire will be harder to fit into the DS). There is also an optional mod to have the Input Interface charge the DS (so you don't need a DS charging cable). These steps are within TAS Mode Installation steps.

Some steps and images taken from the IFIXIT DS Motherboard replacement guide

Nintendo DS Main Circuit Board Replacement

Step 1: Remove game-card and battery from console

Using a Philips #00 Screwdriver remove the battery cover

Step 2: Remove the battery from the console

A "spudger" or pry tool is ideal but using a screwdriver as a pry tool or any other method should work

Step 3: Remove the back cover

There are 7 Tri-wing Y00 screws to remove. The one next to the strap in the photo might not be there if you have a Loopy capture card installed. Once all screws are removed, the back cover should come off without any tools.

Step 4: Remove Motherboard Screws

Use a Philips #00 screwdriver to remove the four screws.