Others have figured out how to midi control bank changes on the BB & VL3 with IOS apps. I do not own a VL3. I use a Line 6 M9. I can now control my BB and my line 6 M9 via Onsong.
The Line 6 M9 has 24 scenes. Each scene has 6 effects and any 3 can be chained to use at the same time. Each scene can be called up with a midi command from Onsong. Note: you cannot pre program which 6 effects in each of the 24 scenes are on/off. It simply loads the scene and will remember the last effects in that scene that were on/off. (maybe there is a way but I did not find this necessary because pulling the scenes is good enough for me).
My set up consists of an IPAD mini with Onsong. I also have ios app Midi Guitar 2 & ios app Sampletank on the IPAD. I run my guitar to an A/B switch. One signal A goes to my Line 6 M9. The other signal B goes to an Irig2 then to my IPAD for midi guitar synth. Both signals go to my small onboard mixer and then to my boomerang. My boomerang then goes directly to 1 channel on my PA. The A/B switch allows me to play either keyboard only or guitar only or mix both signals. My voice goes to channel 2 on PA. And BB goes to channel 3.
I use a PUC+ bluetooth wireless midi interface. The ipad then has a PUC+ app that wirelessly connects the ipad midi out to the PUC+ on my board. Then the puc+ on my board has a midi cable out that goes to the Midi in on the BB. My Midi out on BB goes to my Boomerang looper midi in then my boomerang midi out goes out to my Line 6 M9 midi in for clock synching effects to tempo. As I mentioned, this midi infrastructure now sends midi patch change data of the IPAD to PUC+ through BB through Boomerang to my Line 6 and changes scenes and at the same time sends tempo synch data out of the BB to Boomerang to Line 6 M9.
In Onsong on each song with lyrics and chords I enter this type of midi command. MIDI: 0.28:5, 0:05@3, 0:02@9 It does 3 things. 1. It sends the first set of numbers to Beat Buddy and selects the folder and song (in this case Folder 27 and song 4). 2. It sends the 2nd set of numbers to sampletank that is local on my IPAD to control the guitar synth keyboard patch for the song (in this case keyboard patch 6 @midi channel 4). 3. It sends the 3rd set of numbers to Line 6 M9 to select the correct scene (1-24). In this case Scene 2 @ midi channel 10 (I set the midi channel on the line 6 M9 to 10 in the settings area). Note: I have beta 1.6x firmware on BB. Important: I set the BB to Midi Out: Midi Merge.
I have attached a picture of the midi numbers needed to for each scene on the line 6 M9. Probably will make more sense if you own a line 6 M9. I have also attached an image of my board. Maybe this will help someone.