When I do these hoses, I always start fitting the new hose at the fork carriage end, then to get enough slack in the new hose to clip in in to the WEO connectors I do the following.

Lift the mast up in service mode.

Prop the mast up.

Lower the mast back down in service mode so the main lift chains, pipes etc all go very slack.

Then you can pull the new hoses & clip them in to the WEO connectors.

Very carefully lift the mast back up again in service mode to re-tension everything.

The twin line synflex hoses do stretch once back under tension.