I have holders that will accommodate both left and right handed cutters, you just have to remember to rotate the chuck the right way for the cutter you are using as you mount right handed ones inverted. The holders differ in whether the clamp press the tool up or down.
Not a huge amount of progress recently as I've been tied up with a few other things - example just been making up the latest pork order of 116 kgs of freezer ready pork for customers this afternoon. (Sorry Will-D - that was those two Berkshires!) Also both my workshop PC and Printer decided to die one after the other. PC resurrected but much hassle getting it's Win7 re-authorised having replaced the motherboard, printer sadly terminal and replacement ordered!
However I HAVE actually cut metal with the lathe - not a lot, but just enough to 'set' a couple of tools the old fashioned 'cut and measure' way. The Renishaw HPA Tool Arm is fully working, but so far the only software I've located is a sub-routine that admittedly does most of the work, but the program that calls it is missing.
The Siemens controller is rather convoluted in the way it works. At the high level you have normal G code programs which can call subroutines and / or 'cycles'. Then the Subroutines (which are held in a different bit of memory) can use 'R Parameters' (again in a different bit of memory) as can the 'Cycles' - the cycles (identified with the '@' sign can be very simple functions such as 'jump to location' up to quite complex one such as 'move towards the probe, stop when you hit it, and transfer the X&Z co-ordinates to R parameters'
And just to complicate matters further there are three 'channels' that programs can run in simultaneously - not explored that feature yet

In the case of the Tool Probe Tool Offset program, a set of R parameters hold the location of the probe, and it trots off and chooses the tools one by one, reads their roughly set (by ruler +/- 5 mm) position, finds which way the cutting edge faces from a manually set table, and advances the tool into the probe, hopefully then stopping and transferring the accurate co-ordinates into the Tool Table.
At the moment my puzzle is how to accurately measure the static position of the Renishaw HPA Tool Probe. The slightest contact and it's tip of course moves so darn difficult, especially as you are in free space with no reference planes to work from. I suspect that I'm going to have to make up a 'setting tool' with accurately measured offsets done on a surface plate, measure it with the HPA Tool Probe and make corrections to it's stored location until the setting tool measures correctly.
. . . but other things in life get in the way !