mjm1954 Takahashi EM-200 Temma 2 mount for auto guiding?
There are two ways to autoguide.
One is through the use of an ST-4 cable between the guide camera and the mount (perhaps what you are envisioning).
A ZWO guide camera has basically built in the same electronics that is in that Shoestring USB to ST4 that you mentioned. If you want to use this method of guiding, you have to tell your program to use ST-4 guiding, and tell the program that your ST-4 port is on your camera.
What complicates the matter is that you will need (perhaps you already have) a mini-DIN (the Temma end, called AUTO GUIDE) to an RJ-12 cable (at the camera end). TAC03010 is the Takahashi part number, but you can build it yourself for a small fraction of the cost (I made one up for my EM-11 many years ago). Takahashi produces 4 different style autoguiding cables (where the "camera end" are different connectors). With the ZWO camera, you want the other end to be an RJ-12 ST-4 plug. You can use this guide to build an ST-4 to Takahashi Mini-DIN cable:
https://digitalstars.wordpress.com/2015/04/13/making-an-adapter-box-for-a-takahashi-em-200-mount/
However, you can save yourself all this trouble by using what is called "pulse guiding" instead. Most computer programs today actually assume that you do this when the mount supports guiding (the Takahashi Temma controller has independent guide rates for RA and declination, between 0.1 to 0.9 sidereal rate. Just choose 0.5 sidereal rate for both and it should work fine).
In this second method of autoguiding, autoguide correction signals are sent through your mount's communication protocol instead of through the ST-4 port. Just control your mount by the computer, and you will not need an ST-4 cable.
For this, you will need the Takahashi mini-DIN computer connector to DE-9 or DB-25 serial port, and then a serial port adapter to USB to the computer, unless your computer has a serial port (most do not nowadays). The link I gave above also has the wiring diagram for making your own miniDIN to 9 pin D-sub connector. You can find oodles of 9-pin serial port to USB adapters at Amazon if your computer does not have a D-sub serial port.
Just search the web on how to connect your computer to the Takahashi mount (the connector is labelled RS-232C connector at the Temma Jr. end; I don't know how it is labeled on an EM-200 Temma controller; I only own the original EM-11.
You will eventually want to control the mount from the computer anyway (i.e., turn the dumb Takahashi mount into a GOTO mount), and once you have that, you might as well also autoguide using pulse guiding instead of the ST-4 port on the Temma.
Chen
P.S., many, many moons ago, I had written a MacOS X program called cocoaTemma to control Takahashi mounts (this was back when I may have been the only one on this planet to use a Takahashi mount with Macs).
http://www.w7ay.net/site/Applications/cocoaTemma/Users%20Manual/index.html