using Matlab serial object in a C driver

In my Matlab application I use a Delay Generator connected to a serial port and a PCI time stamping card, which has a driver written in C language. I need to modify the driver of the stamping card in order to use the delay Generator, but I don't know if it is possible to let the C driver to use the serial port object created to use the DG. I need to do it because in my Matlab application I open the serial connection to the Delay Generator, and I need to use THIS connection. Is it possible to pass the reference of the Matlab serial port object to the C driver? I hope I've explained clearly my problem.