Hmm, last year or year before I did actually make a thread for a '
how to'
guide but it would seem as usual mods have deleted it!
To remove the letters you can use a heat gun or hair dryer to loosen the sticky pads of the lettering, next thing is to use something like floss to go behind the letter and drag down to remove them. You'll be left with sticky residue but this comes off easily with some polish.
This may
help a bit
http://www.seatcupra.net/forums/showthread.php?t=289185&page=4
once the letters are off, key them up using sand paper, then primer spray which I got from Halfords, gloss black spray then once dry gloss spray. You'll need more sticky tape to put them back on. I just used number plate tape.