Detecting Browser Support For Specific URI Schemes

I'm trying to figure out if it's possible to detect if a browser supports a specific URI scheme with javascript. So far the only close-but-wont-cut-it solution seems to be looping through navigator.plugins and check for plugins known to support these schemes, but that wont cut it (not maintainable, lacks perenity and have not found such a list). I have HTML anchor tags which use the geo [URL] and tel [URL] uri schemes. These are recognized by the iphone web browser (at least, tel I'm sure of) but not by the more general browsers.

If I click on any of these links in an nonsupporting browser of course, I get a nice browser alert box telling me the scheme isn't supported. But you cant trap that with javascript. I've tried fiddling around with window.navigator and even tried some iframe embedding magic to see if this would work, no success yet. What I want to do is detect I the scheme is supported and if not, prevent the links from a) appearing as links and b) be clickable. So far, I've been able to hack something out of firefox with this:

Code JavaScript:
(function(){
var schemes = ['aaa', 'aaas', 'acap', 'cap', 'cid',
'crid', 'data', 'dav', 'dict', 'dns', 'fax',
'file', 'ftp', 'go', 'gopher', 'h323', 'http',
'https', 'icap', 'im', 'imap', 'info', 'ipp',
'iris', 'iris.beep', 'iris.xpc', 'iris.xpcs', 'iris.lws', 'ldap',
'mailto', 'mid', 'modem', 'msrp', 'msrps', 'mtqp', .....