How to obtain and save the return address inside an interrupt?

I am using MSP430F2618 and the IAR Workbench (version 6.20).
 

 From time to time I get a watchdog reset. I think I can use the watchdog as a timer, then have an interrupt when it times out. Inside the interrupt I would like to find the return address and maybe even save it in flash. If I could do this, I could find out where the problem is.
 

 Would you have suggestions as to how to find out the return address? I know I have to look at the Stack Pointer and may be at some registers to have the full 20 bit return address. But I do not know what exactly I need to look for. ( Unfortunately, I do not know how to program in assembly.)
 

 Thank you for your suggestions.