To start it, make one big meetup that you think will draw people. Make it at an exciting place in the area, chose an interesting meetup topic, or plan a fun activity. An alternative if you're really desperate for people is to draw on the surrounding area by posting in more public places.
From there, all that has to happen is a successful Less Wrong meetup, using the strategies in the OP. That is usually enough to get some of the members to come back a few times, and if the meetups continue being interesting, new members will become regulars.
How to Run a Successful Less Wrong Meetup is a guide that I've been working on, based on lukeprog's instructions, for the last week and a half. As it says in the beginning:
Here's the table of contents:
This is a draft version, so feedback would be most welcome, particularly on things like:
The link above will take you to a Google Docs copy of the document, with the ability to add comments to the draft. Feel free to comment on the guide either as traditional LW comments or by attaching comments to the document itself: both are fine.
EDIT: Here's the most recent version, though without the commenting ability.
EDIT2: The most recent version as of April 11th, with commenting enabled.
EDIT3: First non-draft version; see also this thread.