The kids-rpg Yahoo group has been a great source of information.
I've learned what I should be expecting about attention span from the youngsters and what frustrations they normally encounter.
It caused me to streamline what rules I wanted to present to the children, the duration of the scenario as well as the 'mulligan token' mechanism.
A new source of inspiration is the Chatty DM. I've had the pleasure of receiving a few great tips from the Chatty DM himself.
He suggested that I keep the rules explaining to a minimum.
Which basically means: "The d20 dice determines if something works or not. The bigger the number you roll, the better".
He suggested that I streamline the powers - less choices, less confusion.
Basically: only one "at-will" power and one "encounter" power.
But the golden rule he gave me is probably the one that has the best chance of ending up pleasing the kids: let them control the story.
If you hear them speculate, give them what they are expecting. "If they say 'I bet you there's a Kobold behind that door' - put a Kobold behind the door".
Rings true to my ears.
With these pearls of wisdom, I only need to chop my scenario down to one room and update the power sheets I prepared for their "kid friendly" version.
Hopefully they'll like their first RPG experience...