[Newbies] How to introspect method instance variables

I have defined a method, i.e.,

someMethod anInstVariable := anotherInstVariable1 + anotherInstVariable2.

I would like to intercept the acceptance of this method by the browser and programatically determine what instance variables this method is using so that I can grab these names for other processing tasks.

Additionally, I would really like to be able to determine what instance variables are being assigned to, for instance, anInstVariable in this case and which ones are the "independent" instance variables, anotherInstVariable1 and anotherInstVariable2 in this case.

How can I do this?

Thanks