I just installed the red kit yesterday. I replaced the blue LED in the center storage area with a red one.
It is part:66237SA120 Lamp Pocket
I found it at Subaru Parts Warehouse - Subaru Parts - Subaru Performance Parts
You can probably get it at your local dealership instead, if you prefer.
It took 30 minutes to install. My girlfriend had smaller hands than me making it easy for her to feed the cord. No body panels were removed.
Dartholomew on NASIOC has an awesome post with pics on how to install it. How do you install the Footwell Illumination Kit (H201SSC000) in the '09 FXT/WRX/STI? - Page 4 - NASIOC
I made one small change to his. I installed the drivers side light with the bracket above the hole instead of under. It is similar to the passenger side light installation. I used a socket wrench with an extender for the passenger side since it was impossible to hold onto the nut any other way. A pliers was fine for the driver's side.
The site I ordered from had good prices on the kit too. Even though you have to pay shipping, it kind of is like paying tax. Plus I ordered some other stuff too making it more worthwhile. It will probably take a few days for them to ship it since they had to order the red LED from another warehouse.
Hope this helps anybody interested.