It is possible to use a rice cooker to prepare rice from boxes but it is not optimal.
These box rices typically call for the mixture to be first browned in butter before adding water and flavoring because it is not all rice.
There are bits of pasta in the mixture too.
The rice cooker is able to cook it but the result probably will not be as good.
It is very possible to flavor white rice with seasoning.
I often like to flavor my rice if I plan on making fried rice or if I am lazy and don't feel like making anything but rice.
If you want to imitate a specific flavor, you need to first find out exactly what that flavour is and put that seasoning in the water that cook the rice.
Often though there might be some flavors that can't be added until afterwards.
Such as the cheese flavored rice
you mentioned.
Cheese and rice cookers don't mix.
You would make the rice then later add a cheese sauce that you made.
Please note that one main difference that might occur is slight difference in moisture content.
From the box rice I've made on the stove in the past, I know it is a bit more "wet" than rice made from a rice cooker.
In my answer here , I explained how a rice cooker works.
Essentially it will continue to cook until all the water has boiled away.
cooking.stackexchange.com/users/8305/Jay
I ran across this post while looking to see if it could be done and, truth be told, I couldn't find much.
So, I took a flying leap and tried it myself, with great results!
Here is what I did:
I have a box of store brand beef rice & vermicelli (6.8 oz box)
andI followed the microwave directions at first:
In a round ( for even cooking ) 2-quart microwaveable glass casserole dish ( because some plastic isn't microwave safe and most metal isn't ) combine the rice/vermicelli mix with 2 tablespoons of butter/margarine ( DO NOT USE SOMETHING WITH LESS THAN 56% FAT OR YOUR FOOD
WILL BE GUMMY.
Learned this the hard way. )
and microwave on high for 1 minute.
Stir butter and rice well, then cook for another 1-2 minutes, until the vermicelli is a light brown.
(IN AN 1100 WATT MICROWAVE DO NOT COOK FOR MORE THAN 1 MINUTE OR THE VERMICELLI WILL BURN)
This is where I went "off box": Place in rice cooker, flatten on bottom before -gently- (gently because if you pour fast the rice gets kicked up and you can't see how much water to use)
adding 1 inch of water over the top of it.
(People usually mention the first knuckle on their pointer finger as a guide, but if you're shorter, like me, or taller than average this "measurement" is useless since your knuckle will be less or more than an inch from the tip of your finger.) After adding the water, gently stir in the seasoning packet, then cover and cook as usual.
(My cooker only has one setting, so if yours has multiple, set it for white rice.)
Came out just as good as from the stove top! =D
cooking.stackexchange.com/users/27436/Nojuan Especial
I used chicken flavor Rice-a-Roni.
I have a small Rival rice cooker.
I browned the rice mix in 2 tablespoons lower fat margarine like the package says.
I scraped the rice mix into the rice cooker, added 2 cups of water (not 2 and a half like the package says) and the contents of the seasoning packet.
Gave it a good stir and turned it to "cook".
That's all.
It was perfectly fluffy, not mushy at all.
It stayed nice and warm until the rest of my dinner was ready to eat.
cooking.stackexchange.com/users/51648/Lucy
I would say you can do it, but it wouldn't be advised.
The seasoning from flavored rice out of a box would change how the rice interacted with the water.
You might end up with dry rice, or even soggy rice.
If you are set on doing it, I would suggest a few test runs and seeing what works best
cooking.stackexchange.com/users/8884/dahbearz
I have read the other answers and thought I would try it for myself with Uncle Ben's Natural Select flavored rice.
It turned out fantastic.
cooking.stackexchange.com/users/56892/Christina
I attempted Knorr Chicken Fried Rice.
Mixed using the recommended microwave instructions and placed in cooker.
Let it run it's cycle
- took just over 30 minutes so significant time addition.
Perhaps the pasta included in this side resulted in a moderate amount of sticking on the bottom of the cooker.
The stuck material wasn't too difficult to remove and had a crunchy not quite burnt texture that I found rather tasty.
Unsure
if I will try this again - microwave is almost as mindless and less than half the time.
cooking.stackexchange.com/users/57224/user57224
Can I use a rice cooker to prepare something like Rice-A-Roni's  Four Cheese rice ?  Or what about the Uncle Ben rice boxes?  If not, is there a way to get something that tastes similar without using the boxes?
Can I use a rice cooker with flavored rice boxes?
cooking.stackexchange.com
<rice-cooker>
cooking.stackexchange.com/questions/20809
cooking.stackexchange.com/users/8875/Venesectrix
These box rices are not pure rice, and often require browning before adding water. Cheese is also not a good ingredient to use in rice cookers, but you may be able to cook box rice with an inferior result. You can cook the packet mix in the rice cooker but the result won't be as good.
Cheese and rice cookers don't mix. The mix should be browned in butter first. This is possible in a rice cooker but the result will not be as good.