To set the record straight for any other readers...
No, using regular coffee won't kill you but why waste your timme if you are going to use toxic chemicals?
Every expert I've ever read says to use Organic coffee and filtered or distilled water. And not to worry if the coffee is asorbed into the system. It's fine.
Coffee is a great solvent for cleaning out the colon.
A pure water enema or two should preceed the coffee. A tablespoon of Epsom Salts can be added to help relax the colon if a person is having trouble holding the enema.
You can read about ememas at Curezone in the part that tells how to do it.