Wormwood, tinctures, etc are not used for the liver flush, they're used for the parasite cleanse.
The Liver Flush basically consists of eating no fat for a full day followed by drinking an Epsom Salt mixture then downing a mixture of grapefruit juice and olive oil - timing and amounts are pretty vital for success, so read up on it well first. This allows the bile to build up in the liver (by eating no fat that day) then dilates the bile ducts (the Epsom Salts ) then signals the body to release the built up bile (by drinking the olive oil) all in one big 'swoosh'. The grapefruit juice acts as an emulsifier to help keep the oil down as most stomachs can't take that much oil all at once.
There are instructions, recipes, and variations available here.
BTW, what is SAFI? An herbal mixture? What ingredients?