I used MakeHex and the info from this PDF from JVC.

The PDF has Remote Code 73 (Hex) which is 115 in Decimal. You can use the Calculator in Windows OS set to Scientific mode to convert Hex to Decimal.

115 is the Device Number you need for MakeHex.

Use the "JVC IRP File" in MakeHex and edit it in Notepad to,

Device=115 and save it.

Drag and Drop the "JVC IRP" File onto the MakeHex "Application" File and it will Create a "HEX" File that will have 0 to 255 possible Hex Codes for your Device.

Open the HEX File with Notepad to see results.

The Function Number in the HEX File corresponds the ASCll Code on the PDF, but those Codes are Hex Values which need to be converted to Decimal.

eg.
Contrast = 0A (Hex) which = 10 in Decimal.

In the HEX File this will be the Pronto Hex Code for Contrast,

Device Code: 115 Function: 10
0000 006D 0001 0011 0141 00A0 0014 003C 0014 003C 0014 0014 0014 0014 0014 003C 0014 003C 0014 003C 0014 0014 0014 0014 0014 003C 0014 0014 0014 003C 0014 0014 0014 0014 0014 0014 0014 0014 0014 0336

If don`t want to convert the 0A to Decimal there is an option in MakeHex to display the Function Number as Hex as well as Decimal, see the readme File in MakeHex for more info.

Other Programs you might find useful are,

IR Tools
Decodes a learned infrared Hex codes (only codes that start with 0000) that you paste (Ctrl +V) into the Hex Code Window and press the Decode Hex Button and a box appears to give you information on the protocol, device number and function number. Requires the DecodeIR.DLL file.
[Link: hifi-remote.com]

DecodeIR.DLL
File required by DecodeCCF and IR Tools.
[Link: hifi-remote.com]

Documentation of protocols decoded by DecodeIr.dll is in that .zip file and also online
[Link: hifi-remote.com]

CCF Panels (IR Panels)
Generate a CCF file from the HEX file created with MakeHex.
After creating a HEX file, open it with a text editor such as NotePad.  Use "Edit" "Select All" (or Ctrl +A), then "Edit" "Copy" (or Ctrl +C) to copy all the text.  Then start IrPanels and use Ctrl +V to paste the text into its window and press Generate CCF File. A CCF file will be created in the IR Panels Folder called IRCodesCreate (Don`t use the file called IRCodes Master) that you can use for testing in a Pronto Remote and some others.
[Link: remotecentral.com]

DecodeCCF.exe
Decodes all learned infrared codes in a CCF file and gives you information on the protocol, device number and function number. Requires the DecodeIR.DLL file.
[Link: hifi-remote.com]

Hex2CCF
Generate a CCF file from files created with MakeHex.
[Link: remotecentral.com]

Cheers
Jason