Just thought I'd update you as to use of the inserts. I made a double ended tool, which seems to work quite well. I tried it on a piece of rebar which is a pig to get a decent finish on, even using a freshly ground and honed HSS tool with cutting oil. The tips were held in place with 8BA screws.
I then moved on to the item I originally intended using the tips on. This was in the May edition MEW and has been in my project file since.

When I first tried it it was absolutely awful. I had obviously got the cutting edge too high. Put the main block in the 4 jaw and took a light skim. When re-assembled and checked against the height gauge (just a metal cylinder of the correct height), it looked spot on, but a check with the finger nail showed it to be just a gnats below centre height. Tried a test cut and it worked well. Most of my turning is done with tangential tools, but this will come in where they aren't suitable. It joins my growing selection of specialist tool posts.