I assume you have a remote that accepts codes in Pronto Hex format. Download and install IRScrutinizer. On the Generate tab, pick protocol NECx2, D 7, S 7, and F 7 (for vol up). Then click Generate. Enter other codes in the F box, i.e., 11 for vol down, leaving all the other boxes as is. Make sure under the Options menu that Pronto hex is the Output Text Format.

Having said all that, every possible Pronto hex command is already listed in posts 1-3. So just look up the Function you need, and copy/paste the Pronto hex into your remote configuration software.