Depens what u mean. U'll need to all the files of the game on your pc in oder to ftp it the HDD. But remeber Your pc can't read xbox games. So you'll need to use a program like PxHDD loader to copy a game to the HDD. Then u can back up that folder that holds the game files onto your pc. If u all ready done this then yes u can ftp the game stright the the Xbox HDD. Just need to but it in the right folder. Like I would put it in F:/PHloader/PHgame2.
If you have an ISO file on your PC then use Xfer. It will extract the files from the ISO and FTP them to your Xbox on its own. RustyDog