Use the protocol.

(entries) http://www.livejournal.com/doc/server/ljp.csp.protocol.html
(comments) http://www.livejournal.com/developer/exporting.bml

Follow the rules.

http://www.livejournal.com/bots/

Thanks!

Only if he wants to use the flat mode.

I recommend using the XML-RPC versions, if you're using a reasonable language such as Perl. They're very easy to use and they return data in flexible formats that you don't have to reassemble. You're going to be writing an XML parser anyway if you're getting comments (they aren't available in flat mode).

I had no idea any of this existed, as http://www.livejournal.com/bots/ only mentions the XML outputs and the other comms I was in have not mentioned them. Thanks!

Hmm, going over the protocol, it appears I have to authenticate to the server - I can't just use the interface anonymously. I'd rather design the plugin without the username/password requirement - do I have to do the login?

I don't care anything about wordpress, but you need to learn proper formatting for LJ posts. Trying to use a frame in your post, or whatever you're doing, severely breaks your post. You've got irreparable markup codes, text overlaying the image, a damned SCROLL BAR on your entry, etc.... Whatever you're using to post with is really really borked.

I posted to here using Semagic as normal and when it came out of the queue it looked like that! Don't know what happened there, but the post was validly formatted (or Semagic has a problem in posting to moderated comms).

so i know this may be a stupid question but what is the mark up code for the scroll bar to use that effect on lj? hopefully i worded that right.heh. i want to use it on mine.

No, it's not a stupid question. :o)

It's kind've off-topic to the entry itself though and/or the community (about writing software programs - 'clients', that people can download+use to update their journals; or otherwise interface with the LJ site), which the entry's in though. You'd probably generally have more luck with getting an answer if you tried a community search to locate communities that discuss HTML, to ask there about the markup code needed for a scroll bar/whatever. Otherwise you're reliant on the original poster a) receiving comment emails and b) deciding to reply, assuming c) they know the answer; or, someone else reading the older entry and replying to your comment.
Generally, you can also view page source in your browser, to find out 'how did they do that?'. Because the poster of this entry had a HTML error in their entry the scrollbar wasn't deliberate on their part... so that wouldn't be that helpful. A window with a scroll-bar is a pretty common sight on userinfo pages though, so you could view source at a page like that to see the code. HTML tutorials on the web e.g. lissaexplains.com are helpful too.

Since I'm commenting already... and I know I wondered how people did those scrolling textboxes for ages :)...you can do what you want using the textarea element. E.g:

<textarea rows="4" cols="20">
line 1
line 2 etc.
</textarea>

thank you so much!! sorry it was off topic but you explained it perfectly.

I don't recommend using TextArea to display your data with a scrollbar... it's plain-text only. Instead, use cascading style sheets (CSS) on a block element, such as DIV, with fixed width and height attributes and an overflow attribute, like so:

<div style="width: 30px; height: 40px; overflow: scroll">content</div>