How to Turn <This Bookmarklet> into a Form?

Can anyone help me doing this? I want to turn this bookmarklet:

javascript:try{s1=document.getElementsByTagName('body')[0].innerHTML.toString();s2=escape(s1.substr(s1.indexOf('flashvars.un'),128)+s1.substr(s1.indexOf('flashvars.title'), 128));location.href='http://somesite.something.com/index.html?input='+s2;}catch(err){location.href='http://somesite.something.com/index.html';}

Code (markup):

into a form, in a way that, the user inputs an URL and then click submit to "activate" bookmarklet's function in the same webpage the form is placed. I asked to a few people, but all they say is that "it is tricky" to do... Can anyone do it? I need this to be done and I'm kinda lost here,

Thank you guys

P.S. Any kind of advice or HowTo will be useful.

 

May be this?

<form id='theform' >
URL<br/>
<input name='url' type='text'/>
<br/><br/>
<input name='submit' value='Submit' type='submit'/>
</form>
<script type='text/javascript'>
function mysubmitform()
{
    try
    {
    s1=document.getElementsByTagName('body')[0].innerHTML.toString();
    s2=escape(s1.substr(s1.indexOf('flash'+'vars.un'),128)+s1.substr(s1.indexOf('flash'+'vars.title'), 128));
    location.href=document.forms['theform'].url.value+'?input='+s2;
    }
    catch(err)
    {
    location.href=document.forms['theform'].url.value;
    }
return false;
}
document.forms['theform'].onsubmit=mysubmitform;

</script>

HTML:

 

@parsanthmj: Didn't work... Another way to do it?