TMS-RGB is Open Source Hardware and can be built from scratch using standard SMD procedures. You'll have to order a PCB and all the components from an electronics supplier. You'll probably want a solder paste stencil, which means you'll need an oven or hotplate to reflow the solder paste. If these things sound familiar, read on.
Designing the mod to fit under the graphics chip required reasonably small components, so it might not be the easiest board to assemble. However, some care was taken to make sure everything could be placed using only tweezers and a steady hand.
Making a single board isn't usually very economical but if there isn't anyone in your region selling assembled boards, this might be your only option. If you're planning to make a run of boards to sell to others, this is the guide you're looking for! In that case, you may also be interested in the companion test jig for quickly testing just-assembled boards.