That is not possible, it is all work of the operating system, normally you can get more RAM using SWAP, although the performance drops greatly, especially if you are using memory continuously. You could design on your own a system that will keep continuous readings on disks, or some USB stick as extra memory, even if you also use their disk read.
There is really nothing magical like increasing RAM from scratch, the best thing you can do with RAM is first, choose the best operating system, I recommend a 32-bit Linux system, you could use it without problems with 1GB of RAM, second, 99% of that is dealt with in RAM is always data, that is, graphics, music, audios, etc., rather than worrying about the code you need to simplify this data to a minimum, the amount of tricks for this are too many.
Also, what you are asking is to compile from 32bit to 64bit, there is a lot of cross-compiler related information on the subject, if that is what you are looking for.
You really don't need as much memory to create games, with 1GB or 2GB is always enough, maybe it requires a little more for 3D games with almost HD textures.
You also don't need to test it for other systems except that your game is finished on your own system and you need to compile and correct some possible system or compiler bugs.