Trackback depending on excerpt

in 1.5.0, I dont think I had this problem but I do. when i trackbacked, I used to have like the first 20 text and then 3 “…” after the 20 words and thats how the trackback would look like. in 1.5.1.3, it depends on the_excerpt. How do I make the_excrept grab the first 30 words and insert them in the excerpt so when I trackback them, they will show up when sending the trackback and not show “…” only when it is empty? i tried semilogic excerpt plugin but it says it doesnt work with wordpres trackbacks/pingbacks.