Installing games from an external HDD

[SuperM01]

I'm new in this forum, sorry if I do any mistakes. I have a ps3 with hen, and I wanted to buy a 500 GB external drive to use it on my ps3, I also need to buy a USB to SATA in order to use it, but as far as I know, you also need a USB stick, and I cannot aford to buy more stuff, is there a way where I can download the games, copy it into the external drive, connect it to the console and install the game using the same external drive without using a usb stick? I also was thinking to just buy the usb stick and delete the games I dont need from my ps3 and then install from the usb stick, I dont know. Also sorry if my grammar is not correct, is not my native language. Thanks.