This is a rough step by step...
1. Buy Subaru Flip Key set from Ebay (you'll need the laser key blank)
2. Find a key duplication shop that does laser cutting (high security keys), make sure to tell them that you do not need programming, just a straight forward duplication and you will bring the key blank for it. (Shouldn't be more than $25, make sure to tell them that you do not need any programming.)
3. Take OE key apart (only one screw), install the key fob into the flip key.
4. Remove chip from OE key and place it into the open slot in the flip key.
5. Place spring in, place button over the spring (there's a groove inside the button that will grab onto the spring, so just keep turn it until it locks in).
6. Place key over the button of the flip key, then start winding it counter-clockwise until its all the way down.
7. Place the cover over and install all 3 screws.
8. Test the key, it should flip out pretty quickly. If it flips out slow, you'll need to wind the spring down a bit more.
9. Subaru emblem: There's a clear protective film over it, remove it prior to installing the emblem.
10. I had trouble getting my emblem to stay on the key securely, I ended up using super glue.
PM me if you have questions.