Change search engine in mobile safari on iphone to a different provider?

Is there anyway when a user lands on our webpage to give them the option to change their default search engine in mobile safari to our search engine?

i was on my iphone and went to yahoo and it asked me if i wanted to change my default to yahoo.

is there anyway to program it to have it change开发者_如何学Go to something else for example my search engine that uses the google framework or duck duck go for example? or are only the big 3 providers allowed (bing, google and yahoo)

thanks

Safari only supports the three options shown in in the Settings app.