Yes, setting up Multi-channel MIDI is a common workaround that makes a non-MPE synths act/sound as if it would support MPE. However, you need to do some manual setup to get it working, and editing this MIDI data might not be very comfortable.
You need to copy the same sound as many times as high you want the polyphony to be. Each of the sound’s copies will play only one note and needs to be set up to react to only one MIDI channel. This makes it possible to shape every aspect of the sound for each note individually.
This copy procedure can be done either by duplicating the same instrument track multiple times in your DAW. Or, if the plug-in you use features a multi-channel/multi-timbral mode, you can duplicate the same sound inside one instance of the plug-in.
On Osmose’s side, you need to select the Multichannel MIDI mode. After this, you set the range of MIDI channels that shall be used, e.g. channel 1 to 6 for six voices of independent polyphonic expression. Osmose will now send each new note on a new channel.
By the way: Osmose’s Multichannel mode will also work if you want to control synths that support the so-called ‘MIDI Mono Mode’, originally used for MIDI guitar applications.