Determine point coordinates in screen space

Hello!
I could use some help developing a script to write down coordinates of an object in rendered frame space into a text file. For example, if the object is in right top corner of the screen - the file output should be like this:
objID[x,y,frame]
Sphere1[0,0,0];
Sphere1[0,20,1];

It is similar to a tracking algorithm, I believe, but I need to have these text files for my animations anyway.

The animations will be presented as file sequences, and represent turn-table models. So trajectories of the objects being tracked will be elliptic.

Willing to pay a fee.