You can also "backtrack" the movement starting with the front double biceps pose, too.
Basically, get into that position where you can feel the proper lat flare - now, keep the lats tensed, and let your arms straighten out to your sides in a "t" position (arms will likely need to be angled forward slightly to keep lat tightness, maybe about 10-20 degrees angled forward instead of perfectly straight).
Once you have gotten used to having your lats flared and tight without the biceps being a part via having your arms in the position mentioned above, you can tighten up more and likely increase the flare slightly by pulling your elbows back an inch or two (can be done into the lats or slightly out and away, it seems to work better than a straight pull back) as if you're doing an angled row of the elbows into or slightly away from the lats against imaginary weight. Once you get into that spot and feel it, you can let the elbow swivel and have forearms drop, and you'll be in a decent front lat spread position. It can be hard to get them to fire on command easily, but just think like you're doing a near isometric pull against an object that can't be moved to keep tight and you'll get the hang of it with practice