The only way to get rid of the creosote is to REMOVE it... Converting it clogs the chimney, and that allows CO and other nasty gases into your home. Call a professional chimney sweeper to have it done correctly. I go to a lot of chimney fires with my fire dept, and the best way to prevent them is to HAVE YOUR CHIMNEY PROFESSIONALLY CLEANED OUT AS NEEDED... Atleast once before the start of the season!
Yes, some places use the ABC dry powder "bombs" but sometimes they work, sometimes they don't, and sometimes you need more than one or two, or four or five.. You will also need a ladder to get to the top of the chimney, some way to remove the flue cap, (whats the pitch of the snow & ice covered roof your standing on while doing this too?), the means to drop the bombs or chains down (and don't look down the pipe, you will only make that mistake once) , and start praying they work, and you really kind of don't know they 100% worked either because you cant look down the pipe without getting all the heat and ash and brands in your face. Even so, the bombs don't remove heat, they HOPEFULLY put the fire out, so you still have the heat in the walls, and hopefully that doesn't cause a fire in the walls, if one isn't going already.. So break out your Thermal Camera and check the walls (putting your hand on the wall isn't a great method.. Whats that, you don't have $5,000+ thermal camera to see the heat? Oh.. Start hoping and praying then.... You might be ok.. Or not...) If you do have fire in the walls, your home is now on fire, and you need professional help.... Do you see where I am going with all this?
If you think you have a chimney fire, CALL YOUR LOCAL FIRE DEPT, they have the right tools and experience to take care of the situation. (Thermal cameras, chimney chains, gas meters etc, etc)
Bottom line, unless you like to gamble with your house burning down or not, CALL THE FIRE DEPT ASAP IF YOU THINK YOU HAVE A PROBLEM!
Since everyone likes pics, here are some with some great info! http://www.csia.org/homeowner-resources/the_facts_about_chimney_fires.aspx