This may be the relevant thread.

At any rate, David, try this: Set up ST with the omnisynth sound you want on the melody track. In the VST/DX Synths/Plugins dialog, create a new .tgs preset after clicking Save Group. Save the song. It should now reload configured as you saved it.

Moreover, you can load the .tgs you just created for any track of any song, just by using the Load Group button in the VST/DX Synths/Plugins dialog.

As mentioned in the other thread, you should be able to use this technique with any VSTi, or, for even greater convenience/flexibility, store the .tgs in a modified style with which you may be working extensively. I haven't tested those ideas though (which is why I'm reluctant to post in the tips forum).

HTH, -Ron