The FM2's default focusing screen is a split prism with a microprism ring around it. This is a mechanical film camera with no electronic focus aids. Am I assuming correctly that is what you have?
One thing to remember is that mechanical film cameras expected you to sometimes focus using just the plain focusing screen and it was designed for that. As as long as you have a reasonably bright lens (and it seems you do) you should be able to get usable focus by just looking at the ground glass if what you want to focus on isn't in the center.
The second option would be to center the view on the item you want to have in focus, use the split prism to focus and then recompose to put the focused object in the right place in your composition. Be careful not to move the camera towards or away from the subject while doing this and remember that depending on the shot even small changes in camera orientation can change the focus.
You could also do a mix of those two options, focusing first with the split prism and then checking your focus in the ground glass once you have recomposed the shot.
When I was shooting with an FM2 I found the split prism distracting, and got a focusing screen that didn't have one. I was still able to get in focus.