What a fantastic question! Absolutely it's possible!
$N_2O$ is $N_2O$, whether you get it from an 8g whipped cream charger or a massive industrial tank, it oxidises just the same. The valve you'll need to buy/make for 8g canisters is called a pin valve. Here's an example; basically it is just a hollow needle that breaks the seal when the canister is pressed or screwed into it.
You're not the first to think of using 8g and 16g nitrous canisters in hybrids. There's a test fire of one motor on YouTube. Unfortunately there's very little detail on the design.
However, there are complete motor kits (with cutaway diagrams) if you want to really cut corners. Apparently these motors usually get around 11Ns of impulse, the same as a class D solid motor, so a respectable amount of power for their size.
So go out and do it!
However, always exercise extreme caution when dealing with pressurised gasses. 8g of gas may not sound like much, but one of those little cylinders has enough energy to fire a needle-like pin valve through your eye and into your brain. Always wear eye protection when you're working with pressurised gasses, avoid situations where the gas could propel any object (including its own cylinder), and keep your work area well ventilated.
$N_2O$ is a particularly unpleasant gas to deal with, and has killed many people who thought they knew what they were doing. See SPL's safety PDF for a good summary of some of the often overlooked dangers of $N_2O$.
Finally, any rocket is always just one mistake or failure away from turning into a bomb, and amateur rockets are definitely no exception. Follow the same (or greater) safety precautions you would for a standard solid-fuel rocket when handling, firing, or launching.
Good luck. Fly safe.