here, have some copypasta.
First for Windows (MIDI-OX), then for Mac (SysEx Librarian)
WINDOWS:
MidiOX is available for free from
http://www.midiox.com
Download and install (for PC only)
To send patches to the Little Phatty from your computer:
You must connect a cable from the MIDI OUT on your computer to the MIDI IN jack on your Little Phatty. (or use USB to the Phatty if you have it)
Be aware that if you are sending a single preset, it will automatically replace whatever preset is currently active on your Little Phatty. So, before you send a preset as a sysEx file from your computer to the Little Phatty, go to Preset mode on the Little Phatty and use the Value knob to select the preset which you wish to replace.
an "All Presets" file will (not surprisingly) replace all presets in your Little Phatty
In MidiOx, go back to the Sysex view window (View menu + choose Sysex, if you just opened the program)
Click on File and choose Send Sysex File.
select the sysex file you want to send, and hit OK.
The Little Phatty LCD display will show "Receiving Preset" very briefly, and then you should see the new preset displayed on the Little Phatty LCD. If you are sending a bank of all patches, the transfer will take slightly longer and all 100 presets in the Little Phatty will be replaced by the presets from the SysEx file.
MACINTOSH:
SysEx Librarian is a free program for Mac OSX. It can be found at
http://www.snoize.com/SysExLibrarian/ .
Documentation for the software is located at
http://www.snoize.com/SysExLibrarian/docs.html
Download and install the SysEx Librarian software. When you open it you will find a simple "file player" interface (similar to ITunes). There is a drop-down menu at the top of the Sysex Librarian window labeled "Destination;" use this to select the MIDI interface that connects your Little Phatty to the computer.
drag and drop the .syx file into SysEx Librarian and click Play to send the presets to the Phatty.