At this time, Turbocnc does NOT support tool offset (diameter/radius) compensation. You have to do the offset yourself (either in the drawing or in the cam program). In my case, my solution has been to draw the part in cad, export as a dxf and then run it though Sheetcam (presently in beta, but should be released at the end of the month). Another option would be to draw the part in cad, do your offset there and then run it through Ace converter (available at the Turbocnc site [freeware]).
Hope this helps.