First, to design and implement a functioning version of X-Makina in hardware. The hardware version is to support at least one I/O device (such as a UART) as well as a programmable timer. Interrupt-handling hardware is also required.
Second, a C-compiler, linker, and loader are to be ported to the machine. This will probably entail changes to the assembler. A run-time software debugging tool will also be required.