the problem looks simple , but the implementation will be somewhat hard.
you want a mech device that can press 10 keys , controlled by a pc.
the pc must have a software to program the keypress combination and time.
on the hardware side , you have to design an interface that is connected to pc and output to press the keys. the interface , can be connected to parallel port or serial port or usb.
parallel port interface is somewhat easy to make , serial some more difficult and usb you require dedicated chips.
on the software side, two modules : one to specify the key combination and delay and other a routine to connect to hw port of pc(driver).
so , in all , the expertise reqd is more than that for any hobby programmer and interface enthusiast.