Setting up a usb serial port as a server console

[Robert Moskowitz]

Now that I have 2 Ubuntu servers up and running on boxes without serial 
ports, I am concerned how I would gain access if SSH is hosed (where 
they are is not practical to hook up a kybd/monitor).

I was thinking to get a USB nul-modem cable:

http://www.amazon.com/Suamdoen-Converter-Crossover-Connection-Communication/dp/B09745YD1X?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=A1B9XODBUTQX3J

I would want the server to start a login service on whatever USB dev 
this would come up on.  Plug it in, connect my notebook to the other end 
and run screen and log in.

I suspect I will need to set up something like getty on the server.

My digging for a guide for this is not so good.  Can anyone point me to 
some reasonable approach?

thanks