You should be ok. Just undo the dropper lever from the handlebars so the whole cable can slide easily, remove the battery, loosen the cable retaining brackets below the battery & push/ pull the cable up & out of the seat tube.
Use the existing cable & put it in the new post. Best if you get someone to give you a hand to push/pull the slack cable back down into the battery area & then refasten the lever onto the handlebars.
2 issues I found with the oneup is the barrel of the existing cable was a bit bigger than the receptacle on the dropper post so make sure you fit it in there snuggly or it could move sideways. Also I couldn't drop the post with the trek lever - more pressure was needed so got a Zitto one that has more leverage. I would also recommend checking the grease on the oneup post & redoing - it's an easy process if you look up the youtube clip.
130mm dropper - what were they thinking???