I felt exactly as you describe the first time I thought I'd chew up a clove of garlic...ACK!! There are very few people that can tolerate chewing up a raw clove of garlic! The easiest way to ingest garlic is to peel it, mince it, and throw it in a "gulps worth" of juice, and just slam it back with a chaser of more juicer or water.
Garlic is not necessary for liver detoxification, but it is the best & easiest way there is to kill liver flukes (and certainly cheapest!). These flukes (if they are present) are something that WILL prevent you from cleansing & decongesting your liver if they are present.