How Do I Get Ink Out Of Khaki Pants?

You can use hairspray if it is fresh, also grease lighting (found in most stores in cleaning section) will also do the trick.  Also  you can rub salt onto fresh ink stain on fabric, and soak fabric overnight in milk . Wash as usual.
Also I have found a wonderful product that can be purchased at Home Depot. It is called lift off. They are located in the paint section of the store. It comes in different colors (blue, red, green) for different stain removal. It cost about 7.00 a piece but they work great.
Hope this helps. Have a good day.

I'm not sure of the kind of material used to make the pants, but have you tried using Dawn dish soap?
Hairspray is another item that often works well for removing ink.
I hope this helps!
Sincerely,
rutmar75