As I did not get any response on this issue here I moved the post earlier to another forum. I assumed at the time that this forum was more focussed on functional stuff rather than technical issues.
Considering the fact that this post gets quite some views it may be interesting to know that I solved the problem. I can now connect a USB serial device with either a FTDI or Prolific chipset to my Apple TV and access it from the BASH as /dev device.
The issue and solution is described here :
http://forum.awkwardtv.org/viewtopic.php?f=10&t=2445