console input buffer length

The commands "COPY CON" and "Wscript.StdIn.ReadLine" accept only 254
characters in the console input buffer. Other utilities, such as FTP, have
an unlimited input buffer. DOSKEY is availabe for all; however, DOSKEY does
not have an option to limit the length of the input buffer. A vanilla C++
application that calls cin.get() has an unlimited input buffer (when compiled
and linked using Microsoft Visual C++ Express 2005, but this should hardly be
relevant).
How do I request the input buffer to be limited so that the effect will be
similar to what "COPY CON" does?
Chris