Two micro singularities, contained within a device, that has electrons shot at the event horizon to alter and manipulate a double event horizon between singularities, would be a way of altering space-time. Then you would need computational devices and sensors to lock you into a gravitational field so you can travel physically through time rather than temporally. Of the latter, which would cause you to be in the middle of space somewhere instead of on the same physical plane. And remember, if you travel through time, you will absolutely NEVER return home. You can return to something you think is your home or is 'close enough' but it will never be, 100% the place you originated from. This is a paradox correcting measure that the universe has "built-in". It's literally impossible to time travel to your direct past or future, which is where paradoxes arise. This is seen as time travel in a singular universe or timeline. In reality, multiple universes and timelines exist (in fact.... they are infinite) which is why paradoxes do not exist in time travel. Therefore, if you travel in time, it is 100% plausible to meet yourself without any ill effects to either entity, and it is 100% impossible to change your direct past since it has already been written in time in the timeline you exist in. So in short, you can go in the future or the past, but anything you do will alter another version of "your" timeline, not the timeline you originated from. It's most likely once you leave your origin universe, you will never be able to return to it.