You are going to have to make a dynamic target for the form
where you are going to need to add <a href="http://thelink.com<b rel="nofollow">#parts</b>" target="_blank">
http://thelink.com#parts to the end of the link.
basically you would have to add information like this on the page:
<a name="parts"></a>
whereever you want the page to be returned to.
Now you can use an onclick in the button to accomplish this:
Make a JavaScript function
Now for the button
<input type="button" name="quack" onclick="AddTarget('parts')">
Now you can figure out the rest
Eric