If you're used to trying emulators, is not hard at all. But depending on your skills, it may be quite easy or be very hard. Just read the documentation it has and it should be enough.
Ah, you can also search the internet for guides. I assume there should be one already. Also, you might want to download the NAOMI version too, since its config file has comments that explain its usage. Then, you can use that info to configure the Dreamcast version config file.