Slingshot?
Just use a star's gravitational pull to slingshot you out into space at huge speeds?
they do that all the time. thats what its called. gravitational slingshot iirc. satellites reach their position by accelerating due to gravity of planets. they orbit a few times, then sort of change their position so they're released from orbit and are now traveling faster.
as for finding how to rip through a 4D dimension, it wont be easy. but imho, the answer lies after we find how to detect and if possible, manipulate dark matter and energy. most on the site may know that the amount of matter that we've detected that are present in the universe simply dont account for the maths. we should be gone back into a huge crunch by now. but following models, currently known matter only accounts for 30% of total mass which *should* be present to keep the universe at its present state and for it to behave the way it is doing now.
they give credit to dark matter. needless to say, they are fascinating stuff. imho, its not black holes that hold centres of galaxies together, but rather, dark matter. imho if it were blackholes, it'd be sucking in the entire galaxy.
oh, note a few things. there's little to no air friction in space, unless you get into dust clouds even then, i dont think it'll be a huge problem. all you do is get a conventional drive, load it up with buttloads of fuel. fire it off into space, let it drift into deep space, and then fire it up. it'll accelerate until it runs outta fuel. by then which it should be going pretty damn fast. if you got enough, you might even reach light speed. but at speed of light, or anywhere significantly near, equations of physics get a little unstable. you might want to watch your teacups - mass gets distorted.
back to ripping through space. what you do, is find a wormhole. the name's just stuck. yeah, find a wormhole that links two sides of the universe together. jump in, and you're all set. finding the wormhole, and also where it leads is the trick. thats why i think we need to fully understand dark matter and energy better. they may just hold some answers.