Well, I would agree with the service manual...Clymers isn't always the best source for work on "your" bike...they are more general.
The biggest concern for the choke is that it fully engages when the lever is pushed all the way down. To do this, you need to have all the slack out of the cable. My adjustment would consist of checking this and removing all slack I could. Be careful that you don't take too much out though...you don't want to run around with the choke partially on.