Hi, Welcome to the Forum eljoj !
Here are all important links:
http://lmms.io/forum/viewtopic.php?f=1&t=4740
-A few rules and useful forum instructions
afaik nois it possible to send a midi signal from LMMS to manage the aftertouch of some vst plug-ins.
Some VSTs do have aftertouch-feature, but a general i dont know about
any one else know?? Do chime in!