IF the signals to the MCU are digital, and IF the signal routing is not so awkward or extensive that it doesn't impose any substantial delays due to cable length, etc, connecting them to the same port, and then using a table-lookup to find the address of the routine that processes that particular combination of inputs, is a pretty easy way to handle this.

Any offset required because of signal routing delays can be compensated in this way as well.

All it takes is a bit of imagination.

RE