If you're willing to take the time to look through the IR files on that site for the various receivers, please do so. If you find the code in hex format for the digital input, please post it and one of us will convert it for you. If the function uses 2 command codes, please be sure to post both of them.
As for how you convert them, you just need to convert the hex to decimal (using Excel or the Windows Calculator, etc).
The first byte of each hex code is the device code. Looking at the
VSX-9100 code list, you'll see that most of the hex codes start with "A5", this translates to device code 165. Some of them start with "A4" which translates to device code 164. The second byte is the OBC. So, taking the POWER code as an example, the hex is "A5 1C" which translates to device code 165, OBC 28. Looking further down the list you'll see that the TONE function uses 2 command codes where the hex is "A5 57" and "A5 C0", this means that both parts of the signal use device code 165, the 1st OBC is 87 and the 2nd OBC is 192.
Any upgrade to control a device like this would need to use the "Pioneer 3DEV" or "Pioneer 4DEV" protocols, which let you combine 3 or 4 device codes, along with also letting you generate the 2-part signals that functions like TONE require. The 3DEV version is the official version and the 4DEV version is the one that I wrote myself. The reason that we needed to write our own version is because the official 3DEV version doesn't handle all of the possible 2-part OBC combinations.