For CPT 63650, Medicare does not allow for co surgeons they have a payment indicator of zero. But the tunneling portion as seen below would be included in CPT 63685. But what you are describe does not sound like they are acting as co surgeons for the placement of the IPG. They also do not allow for assistant at surgery so the securing of the lead would not be able to separately be reimbursed for the general surgeon.
http://www.cms.gov/apps/physician-fee-schedule/overview.aspx
From AMA CPT Assistant April 2011, they describe the work included in CPT 63685. The guidance for 95972 you see in the question was prior to the newer requirement for reporting this code.
permanent percutaneous electrode array?
AMA Response: Yes. The use of code 63650, Percutaneous implantation of neurostimulator electrode array, epidural, is not altered when the implantation of the percutaneous epidural neurostimulator electrode is performed for the purpose of a "temporary" trial or for "permanent" neurostimulation. The difference between the two procedures is the attachment of the electrode array to an external stimulator unit for trial stimulation as opposed to connecting to an implanted pulse generator or receiver for permanent stimulation. Attachment to an external stimulator unit is considered inherent to the work represented by code 63650. Therefore, it is not appropriate to report code 63685, Insertion or replacement of spinal neurostimulator pulse generator or receiver, direct or inductive coupling.
However, if the percutaneous electrode array is attached to an implanted spinal neurostimulator pulse generator or receiver, then code 63685 would be reported in addition to code 63650, for the insertion or replacement of the pulse generator or receiver.
Code 63685 includes the creation of a subcutaneous pocket made to house the stimulator and tunneling of the electrodes to the pocket. The generator is then placed in the subcutaneous pocket, lead impedances are tested to verify proper connection, and the device is programmed to begin stimulation (code 95972). (Refer to Question 3 for further information related to the use of code 95972.)