Hi lolpo, here's how I find my seeds for 3rd gen:
Open reporter, 4th gen tools -> claculate PID from ivs, select the spread you want with the nature you're looking for, then press Find, right click on the seed in the small window and then select "Set Seed", press OK.
Back to the main window, copy that seed and go into researcher, select LCRNGR, paste the seed, use max results 1000, then copy the seed in the 1000th frame (the last one) and put it back in reporter's main window, generate for method1 (or the method you chose, you'll find your target spread nearby so it's handy if you want to rng on E with ram hack :p