Output sorted XHTML table for a subset of elements

I've been having a problem with a stylesheet I'm creating and need some
help with a part of it - given the following XML snippet:

<users>
  <user name="alf">
    <lines>7</lines>
  </user>
  <user name="bert">
    <lines>78</lines>
  </user>
  <user name="charlie">
    <lines>731</lines>
  </user>
  <user name="derek">
    <lines>62</lines>
  </user>
</users>

..what I'm trying to achieve is an XHTML table with 5 columns and
however many rows are necessary (imagine there may be a hundred or so
users) where the items in the table consist of only the users where the
user's line count is above 25 and is sorted by their line count.

<table>
  <tr>
    <td>charlie (731)</td>
    <td>bert (78)</td>
    <td>derek (62)</td>
  </tr>
</table>

..obviously with more columns per row and more rows depending on the
size of the input document.

I've tried to do this using a template matching the next-siblings of the
users to achieve the grouping, but then I can't sort the items or select
the ones I want because the XPath works on the input node set and not a
node set I've selected myself (using for-each or a template).

If it makes any difference I'm using libXSLT 1.1.22 to do the
transformation.

Thanks,
Steve