Use system() to invoke Kermit-95 or similar software. Or configure PPP on the two systems https://social.technet.microsoft.com/Forums/windows/en-US/5858797c-bc75-4e3f-bca4-d988fadd7581/setting-up-a-ppp-connection-using-communications-cable-between-two-computers?forum=w7itpronetworking and use MATLAB's ftp class or use SCP or similar, perhaps by invoking PuTTY
As it is "very important" you should not attempt to code the copying yourself: there are a number of difficulties that are difficult to address within MATLAB, many of which are only clear to people who grew up hacking in the days of 1200 baud and 9600 baud modems over telephone lines.
