Emu LaunchPad sends normal MIDI events, so you should not need to send SYSEX messages to control the ESI-4000 in the same way the LaunchPad controls it. I do not have an ESI-4000, so I can not be sure of this, but I do have a LaunchPad. With the exception of 1 button, it sends straight MIDI events (no SYSEX) which means that you should be able to use any MIDI controller (including software) to control the same ESI-4000 parameters as the LaunchPad.

Mitch
The Sonic Spot