If what mingot told me about FR/LG's RNG is correct (that it stores the current seed in your save file), then I just thought of a possible implementation of this in those games as well.
1) Load your game
2) Sweet Scent a pokemon
3) Check its IVs and nature
4) Input them into Mingot's seed finder and take note of your Monster Seed*.
*The initial seeds it gives you will all be incorrect, but that's irrelevant because if your starting seed is the same every time, the monster seed is an acceptable substitute. You will adjust the timing later to account for this.
Also, Sweet Scented pokemon will not work with the current seed finder, because it cannot work backwards from anything other than method 1 PIDs. Until it can, you will have to use an in-game legendary. But that's OK, as you will not be saving the game. So go ahead and catch what you plan to SR, and check it for now.
5) Input the Monster Seed as the starting seed on RNGReporter.
6) Adjust the IV/nature criteria to whatever you want, make sure "starting frame" is set to 0, set the "frames to search" to however long you're willing to wait, and go search frames.
7) Make note of the frame you want to use. The delay outputted by RNGReporter will actually be the number of frames past your initial seed after which the one you want shows up. Input this number into emloop.
8) SR your game and start emloop's timer**.
I do not know when FRLG's RNG starts counting frames. It seems logical that, if the seed is stored in the save file, it would begin counting from when you select Continue on the welcome screen. Meaning you should start emloop when you choose Continue.
9) Wait until the timer runs out, and catch your pokemon.
10) Check its IVs, and see where they are on the list RNGReporter generated.
11) Adjust your timing. Since you took some time to catch the pokemon you checked your seed with, you will likely be several seconds off. That's ok, adjust as usual. This is taking up the time between your real starting seed and the seed of the test pokemon you caught.
11) Keep SRing until you get your desired spread.
This is completely untested, and simply based off of my understanding of how the game works based on what I've been told.
Questions:
Does FRLG store its starting seed in the save file, and use it every time until it's saved again?
When does FRLG's RNG start counting, using the saved seed?