For those interested you can use the following SQL snippet to prepopulate the autocomplete keywords

insert into keyword_autocomplete_keywords(search_keywords, search_count, sources, last_search)
SELECT distinct word, 0, 'b:0;', 1263372541
FROM search_index s
where type = 'node'
  and score > 15
  and length(word) > 3
  and word not in (select search_keywords from keyword_autocomplete_keywords);