Many many years ago I wrote the original paper on the Philips Pronto IR code format. There is a program I developed called IRGEN on my web site (www,the-gordons.net) that will produce Pronto Hex and several other IR formats. It works from a protocol file that describes the format of the IR stream so the program can build it with no original source.

At the web site go to the link to programs on the bottom left and when on that page go to the bottom for the IR stuff.