Adb push to /system/app/Vending.apk
Make sure you delete the com.android.vending-1.apk in /data/app/com.android.vending-1.apk
You can also flash this if you put it in a flashable zip compatable with your clockwork; just take a zip folder you previously downloaded and delete the app or apps that are in the app folder of the zip and copy the Vending. apk to it and flash.
Here's a link to a buddy o' mine's thread, that has Black transparent facebook, gingerbread keyboards, and such.
The name's Fernando, all his stuff is compatable with the epic you just can't use his flash script, but you can have your own made, or do like I say in post #13
[UPDATE 3/5/11) 126.96.36.199transparent Gmail markets_transparent facebook_ more