creating replicable animated arm behaviors/keyframes in Character Animator

I'm sorry if this has been asked before, but I am trying to make a tight deadline and need urgent help.  I know Premiere and After Effects (and I used to know Flash 100 years ago).  Using that terminology, I want to KEYFRAME ARM MOVEMENT.  I know that's not how it's done, and CH prefers setting proper arm IK parameters and live dragging handles (or maybe stetting behaviors...?).  That would be fine, I COULD just do multiple takes until I get it right, but the character needs to go from a standard on-camera talent resting position (fingers clasped, hands held in front of torso) to a Vanna White style gesture to either side.  I didn't make the character, but when I try to amend the PSD to set her initial pose at that "crossed hands" pose, I can't bend the arms properly, no matter the IK settings.  If I use the character I was given as-is (arms at side by default), the arms always go back down to start and I have to live drag them one by one into the initial position, and THEN make the appropriate gesture.  If I mess up at all, I have to start over and the arms go back to the sides.  Trying to blend takes won't work if the default is arms at the side when I want the default to be hands folded in front.  I would like to set a behavior, but it seems I can only do that in "rigging" mode, but I can't move the character unless I'm in "record" mode.  The character won't stay in place for me to jump back to "rigging" mode to for me to say "HEY! this is what I want her pose to be MOST of the time."  I hope that makes sense.  I have perused every video I could find on arm IK, keyframes, and rigging, but they don't answer this question in a way that seems pertinent to my problem.  I have attached screenshots.  Thanks in advance.