How might I find the pinouts for a bluray laser assembly, or figure it out in the absence of one?
I'm going to answer the question at the bottom of the post, as I cannot figure out what else you're asking..

The people who hook laser diodes up to batteries are essentially the rednecks of the laser community. I'll tell you why.
Lasers, unlike most other electrical components, have a NEGATIVE resistivity. One might ask "well, Tusk. Laser isn't a material. how do you get resistivity?", I answer by using the temperature. Assuming a laser module has a constant shape 's' and volume 'v' (which most euclidian objects do), the temperature is the only other variable in determining the lasers resistance. This means that as the temperature goes  UP, the resistance goes DOWN. This isn't how most electronics work, and it can lead to some interesting phenomena.
  The most common one that the 'laser rednecks' see is what is called 'thermal runaway'. This is when the laser gets so hot that the resistance plumets, sending massive power through the diode, which burns out after a very short time.  

To answer the question, the people use batteries because it is easy, not because it is correct.

The reason that many users, even proper users, don't use the power circuitry in the housing is because it is very diffuclt to figure out the power system built in, when most other systems are documented well and cost less than 10$ a unit, which makes them easy and affordable to use.

I hope that I answered your question well!
Ciao!