for the OSC, you must use the OSC module. if you open the module editor, select the OSC module and click the "info" tab at the bottom. You'll get all the information you need on how to use this module.
There is a special way to write your messages using keywords. You can find the layer position X and Y keywords in the keyword browser (command alt B). To move around the stage, you must use values from -640 to 640 in X and -480 to 480. But you can also use higher values depending on the ratio of your output window.
To go back to the original thread, you could use a tracking software such as junxion or a home made thing, send a x,y position to modul8, apply it to your layer position. In your layer you can place a white dot on a transparent background (png) and use the trace effect to get your trail effect. Then you can even add sound reactive auto-scale or auto-alpha or any other effects.
If you manage to create your own tracking software, you should be able to code the visual output too so no need to use modul8