Use the keyframe command with the -vc (valueChange) option, and pass a “rand MIN MAX” as an argument. For example, to randomize sphere.tx between 1.5 and 3.2:

float $random;
 int $n=`keyframe -q -kc sphere.tx`; 
	//total number of keyframes in tx
 for($i=0;$i<$n;$i++) {
 $random=`rand 1.5 3.2`;
 keyframe -e -at tx -in $i -vc $random sphere;
 }

To randomize all the attributes, you can write an upper loop in which you change the attribute to be randomized.