I don't think that can be done at this moment.
As an alternative, you could setup a custom weblink like:
Homepage
$If(<Artist>="Linkin Park",http://linkinpark.com,http://www.google.com/search?q=official website <Artist>)
For Linkin Park it will lead directly to the website you mentioned, and for all other artists it will open a google page where the homepage of the artist is likely to be one of the top results. Could be a useful alternative option?
A random thought on perhaps taking this further:
If you have more artists that you want to have a direct link for, I think you should be able to use a dedicated tag that you populate with the specific webpage you want to link to that artist.
Then you could change the formula above to have it navigate to such a specific website using the url information in that tag, or if the tag is empty/absent, do the google thingy.
You'll have to test if that will indeed work. www-url's can sometimes pose problems when used in tags and/or formulas.