I have read your book of Customizing XOOPS, and try to set 'controling block order' written in it.
It is below

line 166 in XOOPS/header.php
switch ($block_arr[$i]->getVar('side')) {
case XOOPS_SIDEBLOCK_LEFT:
$xoopsTpl->append('xoops_lblocks', array('title' => $block_arr[$i]->getVar('title'), 'content' => $bcontent, 'weight' => $block_arr[$i]->getVar('weight') ) );
break;
case XOOPS_CENTERBLOCK_LEFT:
if (!isset($show_cblock)) {
$xoopsTpl->assign('xoops_showcblock', 1);
$show_cblock = 1;
}
$xoopsTpl->append('xoops_clblocks', array('title' => $block_arr[$i]->getVar('title'), 'content' => $bcontent, 'weight' => $block_arr[$i]->getVar('weight') ) );
break;
case XOOPS_CENTERBLOCK_RIGHT:
if (!isset($show_cblock)) {
$xoopsTpl->assign('xoops_showcblock', 1);
$show_cblock = 1;
}
$xoopsTpl->append('xoops_crblocks', array('title' => $block_arr[$i]->getVar('title'), 'content' => $bcontent, 'weight' => $block_arr[$i]->getVar('weight') ) );
break;
case XOOPS_CENTERBLOCK_CENTER:
if (!isset($show_cblock)) {
$xoopsTpl->assign('xoops_showcblock', 1);
$show_cblock = 1;
}
$xoopsTpl->append('xoops_ccblocks', array('title' => $block_arr[$i]->getVar('title'), 'content' => $bcontent, 'weight' => $block_arr[$i]->getVar('weight') ) );
break;
case XOOPS_SIDEBLOCK_RIGHT:
if (!isset($show_rblock)) {
$xoopsTpl->assign('xoops_showrblock', 1);
$show_rblock = 1;
}
$xoopsTpl->append('xoops_rblocks', array('title' => $block_arr[$i]->getVar('title'), 'content' => $bcontent, 'weight' => $block_arr[$i]->getVar('weight') ) );
break;
}
-------------------------------------------------------------
(changing part is ", 'weight' => $block_arr[$i]->getVar('weight')")

By the way how you change THEME.html with this 'header.php'.
I try to think many time, but my skill is not enough to understand it.