Snaps, trigger/sample?

[RyanV]

About 5 years ago, my band and I went to a studio for the first time. We did one song that was kind of layed back and slow, so we had the idea of putting some snaps on time with the snare hits. Instead of recording the snaps, the engineer had a cd of samples and used something to add the snaps on time with the snare track. I know he didn't trigger the snare during tracking, and I know he didn't manually sample each snap into the song. Any ideas on how to trigger a sample like this with an already exsisting track (besides manually sampling)? Thanks- Ryan