I own the HTS and the 100 as well as the 120macro. No you cannot use the 120mm directly on the HTS however you can use it when you combine the 120 together with an extention ring. This will work, I have used it that way.
Having said that, the 100mm together with extention rings and the HTS will give you a higher image quality. Probably due to the fact that the 120 plus extention rings plus the HTS is a non-recommended configuration the DAC corrections are not at the level of the usual quality.
When doing jewelry I most often prefer the HTS + 100mm over the macro. The ability to use tilt to alter my plane of focus and thus getting more in focus at a short range is very welcome.
Not sure how this is with the Macro II. I am still wondering whether I should sell my macro and get the version II. I do need some additional tax deductions this year
