I may be misunderstanding the question, but perhaps the following example could be of use:

#!/usr/bin/perl -w
use strict;
use CGI qw(:standard);

my @table_rows;

push @table_rows, th({-width=>"20%"}, "Hello") .
                  th({-width=>"20%"}, "There") .
                  th({-width=>"60%"}, "World");
push @table_rows, th({-width=>"20%"}, "The") .
                  th({-width=>"20%"}, "Second") .
                  th({-width=>"60%"}, "Line");

print table(Tr(\@table_rows));
[download]

This produces (once formatted):

<table>
<tr>
        <th width="20%">Hello</th>
        <th width="20%">There</th>
        <th width="60%">World</th>
</tr>
<tr>
        <th width="20%">The</th>
        <th width="20%">Second</th>
        <th width="60%">Line</th>
</tr>

</table>
[download]

For this to work, you'd need to call th() for each column separately, rather than the more normal passing of an anonymous arrayref
Hope that helps
davis Update: Beaten (as ever :) ) by Masem. Small stupidity fix