Hej, Cadenza. Given that you have DearVR Monitor plugged into VEP, and the fact that DearVR Monitor is VST3, AU, AAX only, then you must be running VEP on a Mac. The good news then is that you could, if you wish to, use DearVR's free "MICRO 3D" binaural panner plugin (AU) instead of VEP's standard stereo panner, on instrument channels or small instrument-group busses.
I mention this because it might help you achieve the '3D spatialisation' you want, using VEP and MIR Pro 3D both configured for 2 channel stereo, with Finale. I've done something similar, using Logic, VEP and new MIR, all configured for 2 channel stereo throughout.
I create separate dry and wet audio paths, then use new MIR fully wet to produce its glorious spatialised reverb for each instrument position on MIR's stage; while - outside MIR - positioning dry (or dry-ish) instruments in beautifully convincing 2 dimensional space (I'm not interested in height, though it's possible to do). I use binaural panners for each dry instrument audio path, to match the wet instrument positions on MIR's own stage. Then, on mixing these wet and dry audio streams back together (after MIR), I have a very lovely spatialised headphone mix - WITHOUT using DearVR Monitor (which, in this particular case, degrades both the dry binaural panning and MIR's wet spatialisation).
If you fancy trying this alternative, non-orthodox approach, you can do the necessary dry/wet path spltting, routing, binaural panning, and final recombining of of wet and dry audio streams, all in VEP. The crucial step is in selecting a virtual microphone in MIR that produces wide and well spatialised images of fully wet reverb, without having to use a surround speaker output configuration. As a starting point I'd suggest trying out the "Stereo - MIR 3D HOA Capsules" as MIR's main virtual mic, and listening to the fabulous spatial reverb you get when opening out the instrument's width on MIR's stage.
If you discover a different way of using VEP and MIR in 2-channel stereo to produce wonderful positioning and spatialisation, I'd love to hear about it!
And by the way, as far as I'm aware Dietz is the only expert on MIR (by a very wide margin) in this forum - indeed he's VSL's Design Authority for MIR. There is no need to pay any heed to anyone else here trying to tell you (with fake, trumped-up 'authority') what you cannot do!