Hi,
an easy way to do this for one website (does not work for multiple Icons) is to use sitemgr and sitemgr-site
create a website with sitemgr, with only a redirect module as content. Than if you copy the sitemgr-site directory into the egroupware root (yourdomain/egroupware/ ) and register the app you hava an Icon directly linking to the target of your redirection.
You can use the translatio tools to rename the “website” Icon.
Frank