Apart from you`ll fall off at first? Like the idea, have little idea of how to do it. ( May be getting a steel box section welded. Internal linkings possible?) Plans would have to be simple enough for an unimaginative Chinese bike repairer to be able to follow .
Look at pictures at bent manufacturers websites. They can give you a lot of good ideas.
Simplest methods I can think of are a standard stem pointing towards the seat (like on the HPvelotechnik Streetmachine GT). Closely above the frame tubing. Or weld a homebrew stem to the fork (Like on the Challenge Hurricane Sport USS), just under the frame tubing.