hi mike,
Checked, the 12R will limit the current to 104mA , as per your calc.
Do you have a 6.8V 1Watt zener in your scrap box?.
You could connect this across the battery terminal points from the charger.
If the charge voltage exceeds 6.8Vthe zener/battery it will start to sink the 104mA and hold the voltage to around 6.8V.
If you dont sink or clamp the voltage in some way, the current limit is going to try to drive 100mA into the battery, the voltage will keep rising until the battery fails.
It will work, but I still don't consider it a good idea, LiMH isnt very forgiving.
The attached circuit is closer to what you are looking for.
Remember to increase the value of R3 to reduce the current.
Eric