

Just requires 2 steps performed on the VST.
Step 1: set the VST you want to control with IX Split to the MIDI channel IX Split is on (e.g. if IX Split is on channel 4, set the VST to channel 4)
Step 2: set the MIDI range from C-0 to C-0 in the Edit -> Settings menu on . If you happen to be using C-0, use C-12 to C-12, just pick a note out of the range you are using that you don't plan to hit. Basically the idea is that you only want mod wheel and pitch bend coming through for the VST in question, and the note range is selected via IX Split.
Now pitch bend and mod wheel are working with very little configuration.