I've done this and it works. I actually read about it on here, I think it was called a "co-poo". I would use more conditioner than shampoo. I would just mix them in my palm and use that to scrub my scalp. The consistency was a bit watery but it got my hair and scalp clean.
Have several allergies and sensitivities.
Current products
Low Poo/Cowash: Rio Grande Herb Co Negrita and Amole Deep Treatment Concentrate, Magick Botanicals (MB) Shampoo (diluted)
Rinse out/Leave in: MB with apricot kernel and jojoba oils added
Protein Treatment: MB Conditioner for Thinning Hair, IAgirl's protien treatment
Style: MB Gel mixed with LOTD Aloe Vera Gelly

2b-c, need lots of moisture, likes protein in moderation.