I use it sometimes...I have about a 65% success rate. When it works, it works really well. I like this technique when the patient has a lot of soft tissue flab and I find it tough to landmark for the IANB without putting my finger in next to the needle. You have to give an entire carpule, and it can take up to 5 minutes to take effect.
Basically, you align the syringe with the corner of the mouth and the tragus of the ear, about 2/3 of the way up to the maxillary tuberosity. You come across from the contralateral premolar. Be sure to aspirate.