3) Get a new guide and remove just enough of the insert (using a file or Dremel tool) to leave a nub which will keep the guide from slipping. The cable tension will keep the guide from moving around. I am assuming that you are referring to the guide which goes under the bottom bracket shell.

You could use rubber cement to attach the present guide; just apply the cement to the guide and press it into place. If you do this instead of putting the cement on both surfaces and letting it dry before placing it, the cement bond will be very easy to remove if you need to but will hold enough to keep things in place..