The above instructions are for Pioneer.irp. However, your question made me look more closely and Pioneer2.irp can be used to do this more easily.

So here's an alternate (and simpler) set of instructions.

Edit Pioneer2.irp. The first 3 lines should look like:
Device=166.175
Define P=160
Function=0..255
Now you can drag this file onto MakeHex.exe and get the file Pioneer2.hex. Rename this to 166_160.hex or something like that, because MakeHex will overwrite unless it is renamed.

Edit Pioneer2.irp again and change the 160 to 161.
After running MakeHex on that, you'll have a second Hex file.

There's no need to combine codes, or delete lines. For Play, which is command 166 function 160 plus 175, function 169, just use the Hex code from the first hex file, at function 169. For other functions, which use a prefix function of 161, use the second Hex file.

Do make sure to use IRTool to check your work