Hi, welcome to the forum.
I'm not too familiar with every MIDI CC, but I don't think switching between oscillator modes is immediately accessible.
It's possible you may be able to do it with SysEx, however:-
VirusTI-SysEx-BankA-D.pdf
From the above:
Oscillator 1 model = Page C, CC29
Oscillator 2 model = Page C, CC34
Oscillator 3 model = Page B, CC41
However if it is indeed inaccessible to you, could one possibility be to make a Multi containing several identical Singles, each having different oscillator modes preset, and then switch between them within the Multi when needed? Of course if you have tweaked any knobs in a live performance these would be reset when you switched between each Single.
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PS > And another thing! Will the Ti|3 have user customisable/importable wavetables?

A ribbon-controller or XY-Pad might be nice, too, please! Thanks!