Running BitCoin Wallet On USB
Perhaps it's just an issue with the code block, but I only see one double quote. I assume that the other is before the entire code block, and is used to pass the program name.

The only other possible issues I can think of are to


make sure the directory specified in the datadir argument exists and is writable
make sure that the USB drive is mounted on H:\ on any other computers you use. Maybe it would be smarter to use a relative path instead.


Regarding portable Litecoin etc.
Any program is portable, as long as all of its dependencies can be met in a portable environment. Therefore, if you copy the entire C:\Program Files\Litecoin folder, you should, in theory, have a portable program, provided you copy your data directory also, or don't mind re-downloading the blockchain and don't mind losing all your Litecoins.