No man, that isn't possible. Your PS3 and Laptop must be connected together for the transfer process.
Buy a splitter, it has multiple Ethernet ports that hooks up to the single port on your modem giving you more than one Ethernet port for the same connection.
PS: You can't get everything off the PS store with this method. This doesn't give access to stuff that you need to pay before you can get it. It'll only work on stuff that can download on your PS3, so if you can't start the download, you can't have it at all. This isn't piracy.