macroScript Next_Key ButtonText:"Next Key" category:"Vin" internalcategory:"Vin" ( max key mode max time forward max key mode )
You might have guessed it, what they do is toggling the key mode, going back/forward and toggling again. So if you activate the Key Mode Toggle, the behavior of your shortcuts is inverted. I personally assign these macros to Right and Left Arrows, to keep it like in Motionbuilder, and it works super fine! See how to use macroScripts here.
macroScript Prev_Key ButtonText:"Previous Key" category:"Vin" internalcategory:"Vin" ( max key mode max time back max key mode )