This consists of a robust lump of aluminium with a Taig slide mounted on it. It is intended to clamp to the Taig cross slide via T-nuts. I am sure I have seen these referred to as 10-32 screws. This is very close to M5 and, in mine, they appear interchangeable for this particular job. The plate at the back allows you to align it exactly parallel with the cross slide on the Taig.

There is not a vice on the vertical slide but it is T-slotted so that parts may be clamped to it. As new, it comes with a pair of mild steel bars bolted to the slide. The top bar has three cap screws which pass right through the bar. Simple block shapes can easily be held using these.

An obvious place to mount the slide is in place of the toolholder. If you don't want to modify the slide then drill and tap two holes in the top slide to take the scres supplied with the Taig slide.

Alternatively, you might want to make a suitable hole in the Taig attachment and hold it down with the toolholder bolt.

Either method will do the job quite nicely. The advantage of this mounting method is that you can use the topslide to advance the piece by measurable (small) amounts.

The snag with this method can be seen from this picture.

If you leave the back panel in place on the lathe, the cross slide travel will be limited and the vertical slide cannot be moved far enough. It will not be possible to traverse the full width of a workpiece clamped in the vertical slide.

Also, since the topslide is quite thick, there is a significant loss of vertical movement. The picture shows the vertical slide almost as far down as it will go.

You can't just take a lump off the bottom of the aluminium block as you will then loose part of the dovetail ways. In any case, the leadscrew stands a chance of bumping into the mount if you do that.

Milling attachments on other lathes do not rely upon the topslide for setting depth of cut (z axis). The main handwheel (and a leadscrew handle if you have one) will allow you to do that adequately for most purposes. Turning the leadscrew with the half-nuts engaged will lock the saddle if you don't have any other form of saddle lock.

Take off the topslide completely and you will see a round plate with a peg in it that acts as the pivot point for the topslide. Place the Taig attachment on the cross slide so that it butts up against that peg. Drill and tap the two holes and the attachment will have plenty of travel. in both directions.

For the adventurous (foolhardy?), you could look for a 32 tooth 1 mod gear and attach a handwheel to it. Fix this in place of the changewheels along with one of the 80 tooth gears on the leadscrew. Now, a single turn of the handwheel on the 32 tooth gear will give you 0.025 advance of the carriage. This is a better resolution than the normal wheels. I have not tried this but it sounds fairly plausible :)