mirroring animations - how do i do it?

i'm having a hard time doing animations that need mirroring... 
i can't just hit the mirror button (causes that famous lighting problem) nor can i use the parametric mirror modifier, since it mirrors only the part and not the keyframes...
what i've been doing so far is to take notes of the values for rotation and position everytime i make a keyframe, so i can manually repilicate the movement on the other side...
is there a simpler way to do this that i don't know of?

i can't just hit the mirror button (causes that famous lighting problem) nor can i use the parametric mirror modifier, since it mirrors only the part and not the keyframes...
what i've been doing so far is to take notes of the values for rotation and position everytime i make a keyframe, so i can manually repilicate the movement on the other side...
is there a simpler way to do this that i don't know of?