Hi, I came across this same issue in Ubuntu. I never found a clean way to actually do this. My extra package is to remove wine dependency for i386 (also in rules file) Then both 32bit and 64bit have partial VST support. The full vst package works only on 32bit arch (for the reasons you have noticed) I actually had a very similar discourse with Toby many months ago. I tried every conceivable combination I could imagine and could not force it to work in pbuilder.
So I reverted (for a while) to the simple rules file and let 64bit be without VST and 32bit require Wine. Recently I have modified my version to have the separate VST package (along with upstream LMMS devs adding some code to their CMakelists.txt) to provide WANT_VST_NOWINE for 64bit machines and 'partial' vst support. If this issue cannot be solved we should simply revert to the simple rules file and keep wine-dev[i386] in the control This will require wine for lmms on 32bit, but should still make everything work decently. Then once you are ready to add the lmms-vst-full.install you can use the more complicated rules file. -- Regards