Thanks for the answer. I am only needing to swap them out because of internal routing and using the routing tool deforms the end of the cable, needing it to be cut. Meanwhile, mine are already cut to size.

I am thinking if maybe there is a way to glue/tie some cable to the end and pull it through with the frame, so that I leave a guide behind and don't have to take the cables out of the integrated handlebar and stem, then I can mess with the headset and use the same method to glue/tie the old cables to the guides and pull them back... Routing through the frame was not that big of an issue since I could go back to front + I already have the foam inserts there, which might stay in place and provide further guidance. But going front to back might complicate things