As far as I know, iTunes doesn't support synced lyrics for music (they do for video.) If, however, you do want to import simply the raw lyrics, you could reformat the .lrc as plain lyrical text then add it under the "Lyrics" section of any given song. It might be possible to script it as well.
First, let's understand the .lrc file format. In essence, it's just plaintext with extra tags for information. Since the tags are enclosed with brackets (
) (with additional timestamping enclosed in angled brackets (
<>) for the enhanced format), all you have to do is remove anything that fits these criteria. From there, it's trivial to add lyrics. Simply right click on the song in iTunes, click "Get Info", then "Lyrics", then paste them in.
Alternatively, you could just Google the lyrics.