Just make them download to desktop then:
Go to "My Computer"
"Local Disk (C: )"
"Program Files"
"HTC"
"Aces High II"
Then copy them from your desktop to that last folder and replace the old sounds, sights, skins. and youll be ready to play. You dont have to install these but the default sounds and sights suck. The skins auto download when you play the game but if you DL the package from here you get them right away instead of them one by one for hours.