Hello John.
I have not used this type of tool either but have made several lathe centers using the top slide of my Clausing lathe, but am getting prepared to mount a taper attachment.
We have similar problems with respect to the taper attachment in that I have a very similar appearing attachment. I may be overstating the obvious so please bear with me as I go through what I have learned to date.
1. The bracket on the side will attach to the lathe carriage. It slides along the bottom of the attachment as the carriage moves left or right.
2. The clamp on the right side obviously secures the taper attachment to the lathe bed near the tailstock and prevents it from moving. In my case I have to make a right hand bracket and a carriage mount that holds the taper attachment (TA) parallel to the lathe ways in all three directions.
3. You are missing a "follower block" that slides on the top guide which is set to the taper angle. A rod connecting the carriage cross slide to the follower block is also missing. The end of rod at the follower block must be made to adjust to the different angles set on the TA, and once set be able to be tightly secured to the follower block. Various diameters of stock may affect this attachment. As you stated you will have to disconnect the cross-slide lead screw and remove that nut when using this type of TA. In my case I intend to make this block heavy enough that it will follow the adjustable slide easily, since my slide has no dove tails.
4. As I understand the turning procedure the cutting tool is forced away from the lathe centerline as the tool is moved towards the head stock, which IMHO requires light cuts.
I am certainly willing to to discuss this project through PM to clarify any confusion.
Have a good day
Ray