I think you are combining them ok, it just needs some tweaking. Is there a specific part you are not understanding.
Not sure if there is a tool, but here's a bit of code I cobbled together, see if that helps you understand combining transforms.
jsfiddle http://jsfiddle.net/8R5b4/2/
s = Snap(1000, 620);
var c = s.circle( 200,200,10 );
var r = s.rect(200,100,100,100,20,20).attr({ stroke: '#123456', 'strokeWidth': 20, fill: 'red', 'opacity': 0.3 });
rclone = r.clone();
rclone2 = r.clone();
rclone3 = r.clone();
rclone4 = r.clone();
rclone5 = r.clone();
rclone.transform( 't100,100');
rclone2.transform( 'r20,200,200' );
rclone3.transform( 'r40,200,200' );
s.text(350,150,"rotate around 200,200");
rclone4.transform( 't100,100r20,200,200' );
rclone5.transform( 't100,100r40,200,200' );
s.text(450,250,"combined translate of 100,100 and rotate around 200,200");
For the transform string.. t=relative transform, T=absolute transform, s=relative scale, S=absolute Scale r=relative rotate, R=relative rotate
relative means it takes into account previous transforms to accumulate. Here it doesn't make much difference, but worth bearing in mind