My friend Trevor told me an odd way of cooking the frozen vegetables that I bought from Costco recently. He said to start off making a pot of rice in the rice cooker, then just before you start the cooker, throw in some frozen vegetables and then press start. I've done that a few times, and it works well. There is only one bad point about this. I think the "rule" my Korean friends have given me in the past must be changed when dealing with "vegetable rice". That is, usually I've been told the rice can stay edible and tasty up to 48 hours in the rice cooker (once it cooks the rice, it constantly keeps the rice warm). After 48 hours, you should throw out the rice or use it to make fried rice. My observation is when you have the vegetables mixed in, it lasts an even shorter time - I would guess 24 hours at the most.
I've tried to make a cream of chicken-like sauce to pour over the rice. I've made it a few times, and I'm still not quite happy with it. I think I need to add some spices, but I don't know which ones. I put chicken cubes into cream of mushroom soup, and pour over the vegetable rice and eat it.
While the cream of chicken sauce is definitely NOT Korean, putting "things" in the rice cooker with the rice actually IS a common thing in Korea. Sometimes they put some other, colorful grains in the rice. I've seen different kinds of beans added to the rice, too. My cookbook that came with the rice cooker shows all sorts of variations, if only I could read enough Korean to understand it.