How to run 2 functions which use same serial port object simultaneously

I have 2 functions that are not dependent as such but they use the same serial port object. Also one function has a loop with delay while other is a loop that runs continuously without delay. How do I run them simultaneously? I tried opening two instances of MATLAB but I can't use 2 objects of same serial port.

[Walter Roberson]

Is one outputting and the other is inputting? If both of them need the port in the same direction, how will you be able to tell which I/O is for which loop?

[AnG]

Yep, one is inputting and other is outputting. I am using this package to interface - http://www.mathworks.com/matlabcentral/fileexchange/32374-matlab-support-package-for-arduino--aka-arduinoio-package-