We don't have a Csound plugin for LMMS yet (it's a suggested project on the wikipedia developer section) but in the mean time it's possible to generate plugins with GUI through cabbage. You can generate VSTi and LV2 instruments and Ladspa plugins. Just maybe the VST's generated could work through vestige?
Cabbage site
Cabbage source
Video tutorial
Disclaimer. My workstation is down so I haven't tested Cabbage yet.
Edit: update subject
Cabbage site
Cabbage source
Video tutorial
Disclaimer. My workstation is down so I haven't tested Cabbage yet.
Edit: update subject