I tutor a kid who just immigrated from Taiwan, and he's having trouble learning the language. It took me about six months to realize that it's not that he doesn't understand what he's reading, but rather he's thinking in two different languages, and he's getting confused as to how to answer me. Just wondering if there are any tricks so that I can help him a little better.

The student has to sort it out for himself... Many interpret english in to their home tongue and try to distiinguish the results...
Keep working with him. English is spoken in Taiwan and Korea as second language...

get one of those talking translaters or the book and when you guys want to talk just use it to clear things up

It's called first language interference. Since you are tutoring him, take some time to let him use his first language to his benefit. This code switching can help him figure things out, and might help him with acquisition. If you can share (have him tell you what things mean in Taiwanese, or how the structure varies), it might help him sort things out on his own. It's a natural part of second language acquisition, and it will work its way out on its own. I wouldn't try and suppress it.