You can download it
here (SH3 section of downloads at subsim.com). If you use it for SH4, though, you'll have to do some jerry-riggin to get it to work correctly (keeping a copy of the commands file that you work on with setkey and then copy pasting JUST the key assignments into the commands.cfg in a mod folder or in game). There's a thread around here somewhere that explains how to do it. I'll see if I can find it, too.
Edit : found the thread, it's
here. Make sure you
READ THE WHOLE THREAD or you'll mess up your commands.cfg file. It would be best to work on this in a JSGME compatible mod folder so you can recover you working file if something goes wrong.