Hi i'm looking to upgrade my rail system along my X-axis which is 10 ft. Im wondering what it takes or if it is even possible to join two HIWIN guidways together to make up the 10' run.

Yes, we do that with our machines. You can use the rail blocks to serve as the alignment mechanism. If you have a slight misalignment, the block will not pass that joint. Make sure you use the same rail from the same supplier.