So I've got my flash cart and all, and I'd like to try quakeds, but I wonder if the exram build is going to work... see, quake on the ds is a heavily optimized port that pulls all sorts of tricks to run within the ds's limited hardware, and there's a build that normally requires a slot 2 flashcart to provide extra ram to do fancier stuff (in fact, another port, Quake 2, requires a slot 2 flashcart to run at all), and since the 3ds lacks one such slot, I was wondering if the game can use some of the 3ds' ram (for both ports).
No, it unfortunately can not. When you run a DS flash cart the 3DS runs in DS mode and doesn't have access to the extra RAM.