Train a cascade Object Detector from Workspace

Hello everyone! I'm trying to solve a tracking problem, and I really need to use a the Cascade Object Detector. I've to train the detector "online" during the tracking, so while I'm tracking the object, at the same time I collect positive (and negative) samples into a buffer (a 4D Matrix). When I lose the object (it become absorbed by background) I need to use the Cascade Object Detector to catch it again. Now the problem is that I can't find how to train the Cascade Object Detector from workspace variables. According to documentation, I can only use string filename from my filesystem, not from Workspace.

Anyone knows the solution?

Thanks everybody.