sandiegoguy:
Does anyone know how to accomplish this? I need to declare and construct an object within a function that persists and can be reached by other functions
What do you mean by other functions? Other member functions of the same class?
If so, maybe could you have a private variable (static or instance?, I'm not sure what you need):
SoftwareSerial *mySerial;
When you need to use SoftwareSerial:
mySerial = new SoftwareSerial(signalPin, 0xFF, mode == RS232);
When you're done with it:
delete mySerial;
The compile gives some warnings on the 'delete' operation, so you'll need to make sure the SoftwareSerial destructor properly cleans things up.