CSS3 Column Balancing for Gecko 1.9

I have a lot of difficulties using the CSS 3 column style. I use Firefox 3.6, which should support the -moz-column layout.

I have a list of elements and I am trying to make them in 2 columns, from top to bottom. To help my internal sorting algorithm, the very first element of the list is an optional list.

my css uses this

.container{
  -moz-column-width:635; //slightly wider than the list item we're displaying
  -moz-column-rule:1px solid;
}
.sub_list{
  width:50%;
  display:list-item;
}
.item{
  overflow:hidden;
  padding:0;
  margin:0;
  display:list-item;
  width:634px;
}

Unfortunately, my list is displayed as a single list of columns or a multi-column layout where each one is <li>checked float:left;, but this is not enough because it orders:

1  2
3  4
5  6

This is not what I need, and it looks absolutely disgusting, because the list 1 element is a list in itself.

, , , : http://weblogs.mozillazine.org/roc/archives/2005/03/gecko_18_for_we.html / https://developer.mozilla.org/en/CSS_Reference/Mozilla_Extensions.

- , ? , .