Hi there,
 
I just stumbled over this article... I also always missed the feature in Sonar as somehow Cakewalk never implemented the support for VST-M plugins.
However, I recently found a working solution, maybe it helps others too. (Note that I'm still running a rather ancient version of Sonar, so it may not work with recent versions):
http://www.tonmann.com/2016/10/using-vst-midi-plugins-in-cakewalk-sonar/
 
cheers,
Chris

So with your method using the Wusik-VM, the VST-M (VSTi midi fx or VST midi fx or VST MIDI plugins) will now appear on the MFX list in Sonar (or older versions)? I am not sure that we are on the same page on this. Are we? I am still not 100% sure if I am on the same page with lfm.
 
Is Wusik-VM 32 bit or also 64 bit?
 
Will not get to try this for a while as I am not currently doing any music creation.
 
Thanks for your input.

I believe Wusik-VM is 32bits, there is no info about the bit depth on the homepage and the manual.
Of course, my work-around will not add the VST MIDI plugins to any internal "MFX list" in Sonar, but one can at least use them now.