vector origPos = (vector)llList2String(blah,0);
rotation origRot = (rotation)llList2String(blah,1);
vector deltaPos = (origPos-llGetPos());
rotation deltaRot = llRotBetween(llRot2Fwd(llGetRot()),llVecNorm(deltaPos));
vector deltaRevPos = (deltaPos*deltaRot)*deltaRot;
llRezObject("mirrorObj", (llGetPos()+deltaRevPos),ZERO_VECTOR,origRot,-56);