• Decide on how many Pokémon you need in your party for this particular capture, call this number N.
(This could be 2 Chatots, your capture Pokémon, a synchroniser (or similar, if required) and any HM slaves needed to reach the location.)
• Perform the search with an IV Frame of N+1.
(If you're also going for a PID frame, then it's trickier. You'll want to aim for one relatively high, to account for frames advanced by walking/NPCs. In caves I would suggest ~1500 or so; on grass (if there are no NPCs and you can perform steps not in the grass) then ~800 should suffice.)
• Once you get to your spot, hit your seed as usual.
(You can confirm you hit your seed with (say) 10 Chatot pitches.)
• Now your aim is to walk around precisely 128 steps, and end up stood next to a shaking spot. If one appears during your steps, approach it (do not enter) and finish your steps going 1 away, and one back. This should advance the IV Frame to N+1.
(If one does not appear in your 128 steps, you're gonna have to hit your seed again, and try walking in a different pattern.)
• Once you've done this, use Chatot pitches to work out your current PID Frame.
(The way I have done this is to scroll through the list of Chatot pitches in your RNG Application, and find a selection that will stand out and will be higher than the frame you're on; for example, [Lo,Lo,Lo,Lo,Lo] starting at frame ~1000. Now just keep listening to Chatots until you hear that pattern occur, at which point you proceed advancing your frame as usual.
One thing to note: the final step into the shaking spot does not advance the PID Frame like most steps in an area which might encounter a Pokémon would, so stop 1 before your target frame as usual.)
• Encounter your Pokémon, and bingo :).