CAREFULLY peel the plastic emblem from the grille. it's sitting inside the black plastic oval -- you want to use a plastic car emblem pry type device or a credit card or something as to not scratch the emblem, stick it between the chrome outline and black backing plate
peel it back, it's stuck on with double sided tape
once you have it off you can use something like nail polish remover or alcohol to carefully remove the blue glitter paint. don't sand it or it'll turn dull.
once you have it cleared, the rest is obvious.
I kind of want to buy the one that goes on the STi grille -- it's bigger and checkered... or I might just buy an STi grille and paint the upper "wing" part black
1.) When removing use a hairdryer to soften the double sided tape (its pretty strong)
2.) when removing the badge use a knife with a thin sharp tip and hammer it into the left hand corner of the badge where the silver star meets the edge. The star is indented there and makes it easy to pound the knife into the corner and pry up.
3.) Once you have the badge removed use Brake Cleaner to remove the paint, but be sure to cover the front of the badge with tape because the brake cleaner will distort the smooth appearance if its gets onto it. I tried nailpolish and its a huge PITA, so just use brake cleaner.
4.) just use some simple double sided tape to put the badge back on.
The 08 WRX's emblem is part of the chrome piece. The STI or 09WRX is held on with just sticky tape on the back. I heated it up with a heat gun and pulled it off. You could also used the dental floss trick to saw it off.
I recently found that goof off is great for taking the paint off the back of the emblem.