The indexer doesn't come with any handy clamping holes, but I supose the idea is for you to add the holes where you require them. As John as shown the way how to set the indexer up, my next step was to try and follow his methodology but within the constraint of my own equipment, and get the best out of the tool.
First job I checked the indexer over as best I could to see if there were any gross inacuracy in its build, I found it to be very good.
Pic showing me checking the face squarness of the ram, (Note to self you could you use this as a cylinder for checking squareness).

Then mark the centre line of the spindle onto the base.

Set it up square in the mill in the X and Y

Drill some 10mm holes for clamping bolts

Note use of jacking screws to stop things moving.
Then on the spindle centre line drill and tap two M6 holes

Then mill up a register bar thats a nice fit in the table slots
Couter boring the holes for the head of the cap screws

I'm using some cap screws that have thiner head than a normal cap screw (they followed me home

)


Setting the register bar up square to the face of the indexer

Checking the alignment of the spindle and register bar


The error was 0.05 mm over 120mm thats good enough for me
Next job as I'm planing to use the indexer on another machine where the register bar will get in the way, set the body up againe in the vice and drill right through the bar into the body so that I can fit two dowel pins in, this way I can take the bar off and put it back in the same place again and still maintain squareness.

Thats it I can put it on and off my mill with complete confindenc that it will be nice and square.

Have fun
Stew