Run the "X50 Editor", then use the "Utility" button and select "Import" - you can pick *.PCG files there.
However most of the Triton PCGs available are Programs for Bank E, which the X50 does not have. Problem? Grab a HexEditor and off we go.
Get http://hhd.df.ru/Download/free-hex-editor-neo.exe for example.
Then, open the PCG file, let's say "ROSE.PCG" and find the 0x00033 position:

"04" means it will be loaded to "Bank E". Change it to 00 for "Bank A", 01 "Bank B" etc.
Then save the file, and import it via the X50 software.
Voila. Welcome new sounds.
There might be some multisample and/or conversion problems, but most of the sounds work very good anyway.
I'm guessing TritonLE/TR series has the greatest compatibility - so check that download section.