Here's another solution that I think works pretty well. I initially thought about going through the apex graphs to set up some bidirectional control, but then realized very quickly that you can run into some "conditional" issues, and the menu items, abstract controls, ik/fk, are pretty complicated under the hood. Then I remembered you can trigger selections by selecting a object, similar to what you see in the autorig component for the hand/fingers. What you're seeing here is a tool that allows you to specify a trigger, and when that trigger is pressed, it will then select any number of specified controls, in this case, the configs for the arms and legs.

Make sure you drop the
am_TriggerSelection.1.0.bgeo component into your
../Documents/houdiniXX/apexcomponent directory.