To whomever takes care for SoftwareSerial, could you please have a look at PinChangeInt and see how unused ports are taken out of play with the #define NO_PORTn_PINCHANGES statements.
It would be useful if this capability existed with SoftwareSerial instead of hacking the code.
Please allow SoftwareSerial to play with other code that needs to use pin change interrupts.
Thank-you in advance for your consideration.