Hi Julien Rochette
USBTMC is based with USB 2.0 Specification, so yes, you can implement it. Basically it's just following the USBTMC specifications and make sure you have the descriptors and USBTMC requests correctly implemented.
We don't provide with such a class in Kinetis USB stack, but it is possible, for further information please refer to USB Test & Measurements class specification
Best Regards
Jorge Alcala