Can confirm I just did exactly what VMB explained in the first sentence of his reply to you in the above posting on both the throttle and clutch cables on my latest build. So simple a procedure it doesn't really need explaining in any greater detail.
Goes without saying it's necessary to start with an over-length cable rather than a too short one.
Just be sure to measure cable sleeve length twice before cutting to correct length. Then simply feed on the brass nipple, unwind and splay the last 1/4" of the cable, pull the nipple to the end of the cable, apply flux, and solder the nipple in place. Basic soldering doesn't get any easier than this.