I had to plan this modification from the start, before even assembling the new IKEA Galant desk. Since the desk was so large and I couldn't really flip over the frame, I had to attach all items, including the pegboards, while laying on my back. I had to drill holes in the pegboard for the legs and the areas where I'd be screwing the desktop to the metal frame. I'm no construction pro so my larger holes in the pegboard were sometimes off, but it all worked out in the end. I attached everything - including the pegboard to the metal frame - with medium and large zip ties.
I believe I spent a good 6+ hours on this project, but I'm really happy with the results. I even installed a USB hub near the front of my desk so I can plug in extra equipment easily.
When it's all said and done, I spent only $30-40 on supplies (zip cables, 2x4 pegboards (x2).