How to add memory to an ARM Cortex Microcontroller
You should be able to find out where the EMC maps to in the memory map section of the datasheet/reference manual. Once you have the address range, you will need to setup your linker to use that space for either data memory or a specific section in which you can locate your data.

If you use IAR, this will be in your .icf file. You can specify the section to place a variable in by using #pragma location = "SectionName".