Love to! LOL.
Seriously, failing somebody to lunge you, cross or remove your stirrups, and put a little grab strap at the front of your saddle. Get him working firmly on the outside rein, hold your reins in the outside hand, pull yourself deep into your saddle. Concentrate on following the motion of his back with your seatbones and allowing your hip, knee and ankle to softly open and close with the motion. When you think you've got it, gradually increase the size of his trot.
A really great test is to pick up *one* stirrup. If you can stay even and square in your saddle while sitting and hold one stirrup, you're sitting correctly. If picking up one stirrup makes you lose the feel, you're bracing in the stirrup and pushing yourself up of the saddle. When you can alternately pick up and drop each stirrup independantly without bracing or losing the feel, you're good to go.