Click the Universal Browser button on the toolbar. It is the second one from the left. Then in the Universal Browser, click the hex button. Then past a hex code in the box, then click and drag the "Drag" button over to one of the buttons on your remote. Kind of hard to put in words but this should point you in the right direction.

I tried the codes in the document from Pioneer for my VSX-820 and they don't work. Let me know if they work for you.