How do you join general vaklu's army on onderon?

Being dark side really helps with this one. Anyway, you should support Ponlar (the rebel in the square) and his cause to dethrone the Queen. Basically, whenever there is a debate over who should be ruler, choose Vaklu. Also, be dark side as well. If you support Vaklu, Colonel Tobin will approach you later in the cantina with a proposal (when you meet with Master Kavar). Take his offer. You'll have to leave Onderon either way, but when you return, you will be on Vaklu's side and his soldiers will fight the royalists alongside you.

You should be on the Dark Side (when you do the Dark Side speech options, these are generally to join Vaklu). Anyway, you just mention that you support Vaklu to people (Ponlar, some aliens talking about who's the better leader, etc.) You can talk to this one lady (I forget her name), and she'll say "I hear you want to support Vaklu," or something to that effect. (If you're on the Light Side, or support Talia, she'll just say "I'm busy, we can talk later.") Say that you'll help her, and you'll do a whole bunch of stuff that gets the Royalist generals fired (or killed...but you didn't hear it from me). You'll want good Persuade and Computer Use abilities to pull these off effectively, but you can do it with minimal ones (I guess...). Anyway, just keep on that line of fire, so to speak, and you'll support Vaklu the whole way through. I think.

Good luck.

The way you join him is wen you got to meat the jedi (forgot the name) on onderon he will ask if you WANT TO JOIN HIM or GENERAL VAKLU just answer wit general vaklu.

The way you get to talk to the jedi is after you solve the murder.