Been a bit busy, so haven't have time to answer. Sorry about that.
Basically, the chip you are using is a voltage regulator. They try to keep the output pin voltage constant in relation to the "third pin" (ADJ or GND).
There are only two principal differences between the adjustable and fixed versions:
1) Variable voltage version tries to keep the output 1.25V above the ADJ pin, while the "fixed" ones target a higher voltage.
2) The regulator needs some current to operate its internal circuitry. It is taken from IN-pin. In fixed one, the current goes out through OUT-pin, in variable it goes out via GND-pin. That explains why the variable one's data sheet specifies a minimum load current (8mA).
However, a laser diode should be driven rather with a current source, not with a voltage source, due to its electrical characteristics. Therefore, to convert a voltage regulator to a current regulator. And, you just need a resistor, which gives at the target current a 1.25V drop. Plus you have to change the wiring so, that the output current goes through the resistor. The principle is well visible in another simple laser diode driver at http://laserpointerforums.com/f65/140-pin-out-59465.html
, using LM317. The resistor between OUT and ADJ defines the current. For MC33269D, using Ohm's law, the current is 1,25/R, or for given current I the resistor R should be R=1,25/I . So for 800 mA, the resistor is about 1,56 Ohms, and for smaller currents proportionally higher. With 10 Ohms, you get 1,25/10 Amps = 125 mA and so on.
By making the circuit a bit more elaborate, one can avoid to have the output current to go through the adjustment potentiometer. However, the principle is the same: A resistor convert the current to a voltage, which is compared with a reference to regulate the current.
-I hope this clarifies what I meant.