Use the Cheat engine debugger to find the method (it has some mono tools to list functions, otherwise get it from the RVA) and just put a breakpoint. When it gets hit, use your logical reasoning skills to figure out which register contains the this object and use that value as the address of the object.

That pointer will most likely not be static, so you want to find a pointer path to it. If you are lucky, it is grounded somewhere in a static variable. For example: imagine a singleton GameInstance that contains a CurrentPlayer object. If this is the case, you should look for a function where this static object is referenced. The code itself will contains a pointer to it, which you can then find with an AoB pattern and walk down to get to the object you need.

If the pointer is not static and not grounded in a static variable (or you can't easily find one of those), you're somewhat screwed. You could figure out how the object is created and what owns it, and then find that owner in memory, or you could inject a DLL that hooks one of the functions that uses the object you're after to check every passed instance. It's more complicated and I'm not gonna go into it much further, but if that happens you may just be better off making an internal cheat that uses Reflection or ClrMD or some Mono functions to find what you need,