I got your email.

I think the NG version of ProntoEdit does not include the dialog to select the system and device values for RC5 in decimal.

But I think all versions of ProntoEdit let you do this another way. You can view and directly edit the Pronto hex.

For example, the vol- command should look something like

5000 0000 0000 0001 0010 0011

Don't worry if the second value is different (non zero) or if the third and fourth are exchanged. The important parts are the fifth, which is the system in hex (10 hex is 16 decimal) and the sixth, which is the command in hex (11 hex is 17 decimal).

If you change the fifth number from 0010 to 0013, that will change the system from 16 to 19.