You did it wrong You tried with pk3 files? Are you using wolfwhisperer? That is the easiest. This is how I have done it.
You need to make some folders:
Naming must be exact.
That easy. Otherwise you can rightclick your newly made "textures" folder, "add to archive", select .zip encoding and make it's name "z-texturesorsomething.pk3", then place in /baseq3. But this is more work.
ad2x1.jpeg should be in the 2x1 width x height (duh), a couple Kb filesize should do it. Then there is ad1x1 and ad4x1 which are otherwise identical.