you don't have to solder it.
its a wedge style bulb. so you just swap it out. might have to do some tape to hold it in place because it may be slightly smaller than the stock bulb.
and the odometer. take out the "blank" plastic. sand it down til its white again.
Tha Kraken: http://www.focusfanatics.com/forum/ford-focus-builds-general-showroom/285082-meet-kraken.html