SI there nay guide to use Vanitygen for altcoin ?
Nay but it's not difficult in the least if you already know how to use vanitygen.
Use the -X option and a number from the table on
this page corresponding to the prefix you need.
For example Litecoin needs an L so you would use decimal value 48
C:\Users\xhomerx10\Downloads\vanitygen-0.22-win>oclvanitygen -d 0:0 -X 48 LTCsux
Difficulty: 264104224
Pattern: LTCsux
Address: LTCsux36wDQkJ8vQ1mUmqSc2AcprwMiZg8
Privkey: 6um9edQTyJk7xjCpaR2WrjNxnf6vhzGAhxcqW8inU4jotDTL9Cc
NB I don't believe that litecoin sucks

Also, it's even easier since
ExploitAgency has created a
fork of vanitygen which I have not yet played with yet but fully intend on testing at some point in the future.