I haven't rooted caapi but have high success rate with other plants. I'd say for sure use IBA (the cheaper powder form is fine) and use humidifier or make a clear plastic dome to keep the humidity in.
Use a potting mix with high porosity (ie a lot of perlite for example), and water very sparingly at first, letting the mix dry out well, to spur root growth. If constantly moist roots will have little reason to grow
Flourescent light 24/7 for awhile also a good idea.
Hope it helps, best of luck!!!
One epiphany short of a paradigm shift