Typing in special characters

I've tried entering _ (shift -) in searches and can't enter the character.

Is there a trick to doing this?

It seems some results will have all_the_words_strung_together, as shown. I'm wondering if a search with the words strung together using the _ key will provide more hits.

Also, are there any other special characters that can be entered and how does one find a list for Limewire?

Thanks.