I have no idea what platform you’re on or what version of Cubase you have so here’s the basic instructions:
Go to wherever your main Preferences folder is stored.
Open the Cubase 7.x folder and navigate to the Scripts folder and then the Patchnames folder. Drop your Mo-Phatt.txt file into the EMU folder.
Launch Cubase. From the Devices menu, choose MIDI Device Manager. Click on the Install Devices button and scroll to Mo-Phatt(EMU) and select it. Assign the MIDI Output connected to the Mo-Phatt.
You’ll now be able to assign the Mo-Phatt in the Output Assignment window in any MIDI track’s Inspector and access its patch list.