Here is the final schematic for your viewing pleasure
Assuming a 30ma rating for the LEDs and a required voltage drop of .7v you can calculate the resistor values of R2 with this formula:
(Supply Voltage - .7)/0.03 = value of resistor in ohms.
(supply voltage - voltage drop of LED
)/(required current value for LED
) = resistor value
this will allow you to use which ever LEDs you wish and still not burn em out.
I would round up to the neares common value you can find.
R3 can be adjusted too far and cause a null 0v no light you can also use a 10k trimpot to make it smaller and fit better on a PCB.
Q1 can be replaced with any simalar small signal NPN transistor.
once i solder all the components to the PCB I epoxied the whole thing except the two variable resistors nice and water tight. Same thing at the connections for the LEDS.
I mounted the LEDS to a thin strip of PVC
drilled holes to fit just the LEDs and then mounted that to the underside of my light. HTH