To flash a radio is simple. You have to download the radio from the link yeahha provided and then put the zip (don't extract) into the root or your sd card, so not within any folders or anything. Then you MUST rename the radio to PCIMG05.zip. Now unplug from PC.
Then boot into hboot via however you want and because pcimg05 is on the root of your sd card, it'll automaticlaly boot and prompt you to install the package which is the radio. Click yes and let it do its thing and you should be good. When you're done, you should rename the file on your sd card or delete it.
Keep in mind the radio and the rom are two different things and you can't do them all at once. you have to do them separately (doesn't matter the order)