Any ASIC hardware designed to mine Bitcoins can only mine altcoins that use the SHA-256 hashing scheme, since the underlying hardware is only designed to perform SHA-256 hashes.
As a result, it is not possible to use Bitcoin based ASIC hardware to mine scrypt based altcoins, such as Litecoins and Novacoins. (The scrypt hashing scheme has heavy requirements that ASIC hardware designed for Bitcoins probably doesn't meet anyways.)
Edit: You might want to take a look at the SHA-256 altcoins listed at
http://altcoins.com/ if you're looking to mine an alternate cryptocurrency.