by escaping them. brackets are special characters for regex expressions that define groups. If you don't want to use that functionality, you put a backslash in front.

example: (twitter) becomes \(twitter\)

Yay! Thank you bunches. It worked. I learned everything I know in Pipes from looking at other people's pipes, but that was something I hadn't come across and couldn't figure out. Thank you.

I don't really understand what you mean by a statement and what part of the parenthesized expression you want to replace ( just the parentheses or the whole expression).
Please supply a link to a pipe or feed and a concrete before and after example.