I've mentioned this before in another post. I've finally got around to doing this so now instead of only one working key for my bike, I have three!
It's really easy to do and will explain as best as I can. There is a YouTube video below that explains how to program the keys on a different Honda bike. Those instructions are the same for the Firestorm. The only difference is that on the 'Storm you've got to remove the front fairing and the cable you need to access is in a different position, but I've taken a picture to illustrate.
This is what you need ---- 1. New spare keys, cut to the lock. The keys need to be the same style as your original so that you can fit a transponder chip inside. The transponder chip must never have been programmed before and the chip must be an ID 46 type. I got my keys from http://www.keysinthepost.com , I sent them a digital image of my key and they sent me two keys, ready cut that work perfectly. I already had two chips, although they can supply those too.
2. You need a special cable to program the keys, like this one: http://www.ebay.co.uk/itm/221173687390? ... 1497.l2649
You have to disconnect the 'pulse generator coil wiring connector' and plug this cable in instead.
Right then, first of all, you have to remove the front fairing of the bike. Remember to disconnect the front indicator connectors, the side light and the main light (you need to partially remove the fairing first to get to the connectors for the two front lights). You also need to remove your mirrors.
Once you've got the fairing off, you need to locate the pulse generator coil wiring connector. This took me ages to find! It is located just behind the left radiator (to the right hand side of the left indicator). See the picture below.

It's that dirty connector with the black wire coming out of it. I couldn't see it at first because it was so dirty, so that's what you are looking for.
Next, you have to disconnect that cable and plug in your Honda HISS programming cable. See the next pic:

Once you've done that, take the crocodile clips on the other end of the cable and connect this to your battery, positive first then negative.
Now, take your ORIGINAL key and put it in the ignition and turn it on (just the ignition, not the engine). Your HISS light will come on and stay on. If it doesn't, then something is wrong. See the chart at the bottom.
Your HISS light is lit solid. Now, disconnect the crocodile clip from the POSITIVE battery terminal for at least FIVE seconds (not two, like it says in the Haynes manual). Reconnect the clip to the battery. The HISS light will now flash four times (and carry on flashing in groups of four). If it doesn't start flashing four times, just try again with disconnecting the crocodile clip. It didn't work for me first time either. What you have done here is erased the codes of all keys from your bike, EXCEPT for the one in the ignition.
Now, turn the ignition off and remove the key. Place that key well away from your bike and get your new un-programmed key ready. Take your new un-programmed key, put it in the ignition and turn it on. The HISS light will again blink four flashes at a time. Your new key is now done.
If you want to, take that key out, put another un-programmed key in. Turn the ignition on. The HISS light blinks four times, and so on and so forth.
You can do this so you have your original, plus three additional keys.
Now, remove your programming cable from the battery. Remove it from the connector behind the left radiator and reconnect the pulse generator coil wiring connector. Now you can try starting the bike with your new keys. Put the front fairing back on, and Bob's your mother's brother.
This YouTube video is an excellent demonstration of the programming stages.

Also, I no longer need my programming cable. It cost me £25 on ebay. I've had my use out of it and I'll let it go for £20. I thought I'd lost my only key the other day (my five year old daughter thought she'd take them to school) and I was panicking over how much it would cost to replace the locks and ECU!! So, I'm glad I now have the peace of mind having three keys to the bike.
Any other questions, I'll do my best.
Gav