Well
The time travel part is the easiest(?) to do. Physically we aren’t at a level of development where it is possible but theoretically here is what you would do.

Locate six dwarf stars of equal size and mass. Move five of these into orbit around the primary and set them all spinning clockwise about there axis. You would then need to set the orbit of the five dwarf stars so that they orbited the primary in an anti-clockwise manner. You would then use the gravitational gradient within the system to pick you’re temporal destination within the light cone (simply the life) of the primary dwarf star.

But please remember that this is all theory that a friend of mine (PhD in astrophysics) and I worked on one night, and we weren’t even in the pub.

Interdimensional travel would be far more tricky as you would need to find a way of breaking out of the light cone of the Universe and we couldn’t see a way of doing that.
(Herr Doktor Lemminge Is bored, so cheer me up!, Mon 1 Sep 2008, 13:52, Reply)