Queries very slow until key cache fills up. Is there a way around this?

[rbnetus]

I'm having this problem where on a new database with MyISAM tables, until the key cache gets filled up over time, the queries are very slow. I've read that version 4.1 supports index preloading which probably would solve this. Until then (I use 4.0.20), is there some way I can get the key cache to fill up quickly to avoid these really slow initial queries. The difference is almost 10(+)x faster performance after a few minutes of usage.
The database I use is mostly a read-only with data pre-populated before the application starts up.
(Table has about 250,000 rows with about 20 columns).
Thanks!
P.S: I'm reposting this in the performance area. I mis-posted it on the newbie area...apologize for repeat mails, if any.