I guess there's no way to determine which keywords trigger when the sitelinks are shown? It would be nice to know what Google feels your site is an authority on.
Google only shows a PORTION of sitelinks that you have using the 'link:yourdomain' command. If your site has less than 10 links, you can forget about anything there. Similarly, webmaster tools does not show ALL of your sitelinks. Some of the links never even make it into it. In general, the higher the PR of the site / subsite linking to you, the quicker your sitelink will appear.
Google shows SITELINK when I search with company name and when I search for keyphrase it is not there even my site is on #1 position for that keyphrase...