I wish to locate a structure to a specific memory range in External RAM. No other data can be allowed to use this memory range.
What I am trying to do is to re-claim RAM for other purposes using XARRAY once the structure values are no longer needed.
Is this even possible using the Keil C166 and L166?
There's absolutely no need to fix the struct's location to achieve your goal. You just have to learn how to take the address of a struct, or better still, what the "union" data structure is for.