After downloading a bunch of files from various places, I finally got emu48 to work with my X51v. In case anyone can't get it to work, here are the files in my \program files\emu48:
1) Emu48.exe
This is the program. Download and install E48MB1xx from
http://privat.swol.de/ChristophGiesselink/emu48.htm
2) beep.48
3) keyboard.kmi
Grab these from
http://www.hpcalc.org/details.php?id=5292
4) ROM.48G
Download the rom from
http://www.hpcalc.org/details.php?id=4368. Unzip it and rename it to ROM.48G
5) EngrPaul VGA Real 48GX.bmp
5) EngrPaul VGA Real 48GX.kml
6) HP48GXVGA.bmp
6) HP48GXVGA.KML
Lastly you need a set of KML and BMP files. I like the ones from
http://www.hpcalc.org/details.php?id=6440 :)