Honestly - if you don't have money to upgrade to a mid-range cpu/gpu set-up - i wouldn't consider try using a gridseed or usb miner as an alternative.
You will actually get more from coinpot's faucets per day (one claim per day for each of their 5 coins is all u need to do), than from trying to mine on equipment with such low hashing output compared with current tech outputs. The litecoin faucet itself would return more than ur gridseed/usb miner can return. And trying to keep your miner connected to a pool that will mostly want to ignore your small hashpower will be another thing you'll have to deal with.
The other issue will be the cashout period. Because litecoin dificulty is so high - you only get rewarded a when the block is solved by a pool and this takes days depending on the pool you mine with, and because your hashing power is low you won't get a huge reward so it will take many more days to receive enough litecoin to get above the minimum withdrawal level...
If you just want to mine solely for the lolz etc yes you can - but its going to take awhile to generate any return.
If you want to get in on some mining action - invesitgate your options for ETN mining if you havent already
