We've only used our liquid detergent for one load of sheets, but I think it'll do okay. Here's the recipe!
Leah's Homemade Liquid Laundry Detergent
1 cup liquid castile soap -- I like Dr. Bronner's lavender, which I bought from my local hippie store out of the bulk soap container
1/3 cup washing soda
1/3 cup baking soda
1/3 cup Borax
1) Fill a one-gallon container with 1 cup of liquid castile soap
2) Add about 4 cups warm water
3) Add all powdered ingredients slowly. If possible, stir while adding. Alternatively, shake frequently.
4) Fill container with warm water until full.
Use 1/4 cup per load of laundry.
I should mention that this recipe is adapted from several I found on the interwebs. If you wanna see my sources, see this recipe and this recipe.
Good luck, and let me know if you try it!