Building a Battery Charger with an LM317
This page apparently describes a LM317-based charger with auto-shutoff, though it has a few more parts than a resistor.

At the most crude, you can use an LM317 and resistor to form a regulated current source, which is how NiMH/NiCd's should be charged.  See "Precision Current Limiter" (p. 19) on the LM317 datasheet.  The regulator functions as a current source by attempting to supply as much current as possible to have Vout - Vadj be 1.25 V.

Note that there is nothing inherent in the LM317 to shut off a charge, so if the batteries are fast-charged (~C/2 or higher), they will fail if you do not terminate the charge at the appropriate time.  With a trickle-charge (C/20), you "can" leave them alone with no ill-effect.

So in your specific case, the 2-part charger would be a LM317 and a resistor to charge the pack at C/20.  


Charge rate: 1000 mA·h @ C/20 =&gt; 50 mA
Resistor value: 1.25 V / 50 mA = 25 Ω


You need to provide a voltage to Vin at least 2.0 V (dropout voltage) + 1.25 V (reference voltage) = 3.25 V greater than the maximum charging voltage.  The resistor would be connected between Vout and Adj, and your load is connected to Adj (not Vout)