I haven't seen this topic added as a sticky yet but I think it will be helpful to people wishing to bring in narcotic based medicine into Thailand as a part of their personal pain management treatment.
Good News! The process has been streamlined.
The permit for travelers carrying narcotics into/out of Thailand website launched December 5th 2015. So this site is brand new.
The process is fairly straight forward.
For Carrying In, (which i followed) involves the following steps:
Entering all your personal details and passport information
Flight information and dates of stay/departure.
Medical information - license number of doctor, doctors addressm description of your treatment, then adding the various medicines that you wish to bring into the country.(This part is really easy, enter the generic name then select the active ingredient and amount prescribed for daily use e.g. Panadeine Forte, Codeine 30mg, three times daily)
Attachments need to include a letter from your doctor that details all of your medicines and the prescribed amounts that you are taking, e.g. 5mg twice daily. A copy of your passport main page. And any other supporting documentation that you wish to attach.
Basically what this website did for me was completing the IC-1 form, which is used for travelers who wish to bring in typical prescribed painkillers that contain codeine and oxycodone based meds.
I have received a confirmation email saying that my request is being processed and now i'm just awaiting the confirmation approval.