The only way I've found to do this is similar to what you described:
- Grab current scroll position (don't forget horizontal axis!).
- Set overflow to hidden (probably want to retain previous overflow value).
- Scroll document to stored scroll position with scrollTo().
Then when you're ready to allow scrolling again, undo all that.
Edit: no reason I can't give you the code since I went to the trouble to dig it up...
// lock scroll position, but retain settings for later
var scrollPosition = [
self.pageXOffset || document.documentElement.scrollLeft || document.body.scrollLeft,
self.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop
];
var html = jQuery('html'); // it would make more sense to apply this to body, but IE7 won't have that
html.data('scroll-position', scrollPosition);
html.data('previous-overflow', html.css('overflow'));
html.css('overflow', 'hidden');
window.scrollTo(scrollPosition[0], scrollPosition[1]);
// un-lock scroll position
var html = jQuery('html');
var scrollPosition = html.data('scroll-position');
html.css('overflow', html.data('previous-overflow'));
window.scrollTo(scrollPosition[0], scrollPosition[1])