Why don't you use apply subd to the chair in Studio before you export it to Octane? I do this all the time exporting stuff to LuxRender. Studio's subd works quite well, especially since they implemented OpenSubDiv.
Maybe I'm doing something wrong. The hands are actually Genesis hands, scaled up to around 500%. When I try to apply SubD, it gives me a warning that SubD is already applied. Is there a trick I'm not doing?
When a figure already has SubD enabled, such as Genesis, go to General->Mesh Resolution in Parameters for that figure. You can then increase the number of SubD levels. By default, this parameter is locked to a max of two. However, you can click the gear icon and untick the lock (or in the case of SubD, consider changing it to say four so you don't accidentally go too high and kill your machine from RAM consumption). For Genesis, I always set SubD to three in all my renders. If you've scaled it up to 500%, you might need to go higher. I'd strongly recommend you tick off visibility on most of the Genesis figure providing the hands (e.g., everything but the hands and forearms should be turned off) to help reduce the geometry load when you export if you've got a high level of SubD.