Hi Madsy,
Firstly, BIAB does have MIDI tuning. If your soundcard supports this, and you are using a MIDI style (as opposed to a style containing Realtracks), it should be able to be tuned.
The option is found under "Options | GM Settings".
If you use Realtracks, it's still possible to tune. I just tried the following approach and it worked for me.
1. I downloaded a free pitch shifting VST from the below URL. It's called PitchProof and comes in 32-bit and 64-bit dll.
https://aegeanmusic.com/pitchproof-specs2. I tried it with BIAB 64-bit. Before doing any thing else, I needed to put the 64-bit pitchproof .dll file in my VST folder (using copy and paste).
3. Next I loaded the song I wanted to work on.
4. Then I opened the MIDI/VST-DXi dialogue window (#1 on the image below).
5. I selected "Combo" (this affects all output) -- #2 on image.
6. Using the dropdown listbox that I've number #3, I clicked on "Add VST plugin" -- this is at the bottom of the list.
NOTE: It's important not to use the top dropdown list box because this is usually reserved for a software synthesiser.
7. I navigated to where I'd put the PitchProof dll and selected it.
8. I then set the blend (#4) to Wet so that only the processed signal could be heard.
9. I set the "Pitch" to zero (#6)
10. I set the key to that of my song (#7) -- this is probably not needed.
11. I then tuned the output using the dial labelled #5.
This worked fine for me and sounded good.
Hope this helps,
Noel