Depends on what you mean by "program".
You would probably need a flash bios or SDRAM to load a program at boot time that would communicate over the serial port and upon command, transfer code in to memory, verify it, and then start it executing. A failsafe timeout that either interrupted or rebooted would probably not hurt ;-)
For some information on the serial port interface, see here. In that thread, Scott recommends highly against using the 8051 with the product that would later get named MATLAB Coder.
