I’ve been using some code shown by @ccstone here to insert XML versions of custom actions of mine into macros I am working on. I can envisage this being altered relatively easily to work with the XML if it is stored in a clipboard or KM variable, rather than being embedded in the code so it could then be considered a way to paste XML actions until it is implemented natively in KM.
Is this the kind of thing you had in mind when wishing to paste XML actions?