I generally shy away from the cryovac'ed sausages because I think they taste weird and unnatural. If you go to Mayflower in Chinatown Square, next to Citibank, they have them hanging above the butcher area. The redder one is pork and the darker reddish brown one is liver...
Simplest way to prepare is to slice and add to your rice cooker or pot when the rice has absorbed most of the water. By the time your rice is done, the sausage will be too. Also good thinly sliced and sauteed with vegetables or fried rice.