Answer:
I'd recommend you don't. I work in a tattoo studio and we get at least 2 people a day come in and ask for a cover up on a badly done, home-made tattoo.
You need technique, that takes tattooists years to learn.
But in answer to your question; You can't. There's a lot of equipment needed which would be impossible to do a tattoo without: Inks, machine, needles, pedal, amp box etc.