As far as I know, no. What I do (I use an emulator) is generate a list of several spreads (normal, alternate and split) when depositing the parents, generate the egg's PID, and when going for the IVs, try each frame in order until I get the desired spread.Is there a way to "reliably" manipulate the game (Emerald) to get alternate or split spreads more constantly? or do I have to be lucky enough to and wait to see one of those two pop up out of nowhere, as usual with Emerald's RNG?
For instance, if frame 3000 gives me my spread using Normal Inheritance and frame 5000 works with Alternate: I go for 3000 first. If I get lucky and Normal occurs with 3000, I'm done. Otherwise I figure out which Inheritance happened and try the next possible frame, in this case 5000. Eventually I get the right spread.
Naturally, using an emulator means I don't have to reset the game everytime I receive the egg - I can just reload the save state. This means that the frame offset between pressing A and actually receiving the egg (usually around 15-30 frames), which normally fluctuates, remains constant (as long as I don't reset). But this could also mean that the game doesn't change which frames will go Normal and which will go Alternate (I believe resetting could change this).
What I've noticed is that Hidden Power spreads, for some reason, take longer to work - that is, for the first few spreads, if Normal would work the game goes with Alternate, and vice-versa - but eventually I also get them right. This very likely could just be bad luck from my part, though.