TYPO3 Core

Unclean solution, but working (is not respecting CType)

t3lib_div::loadTCA('tt_content');

$TCA['tt_content']['columns']['select_key']['config']['wizards']['tx_wizards_uploads_path']
= array(
    'type' => 'popup',
    'enableByTypeConfig' => 0,
    'title' => 'Link',
    'icon' => 'link_popup.gif',
    'script' => 'browse_links.php?mode=wizard&act=folder',
    'JSopenParams' => 'height=300,width=500,status=0,menubar=0,scrollbars=1',
    'params' => array (
        'blindLinkOptions' => 'page,mail,url,file'
    )
);

Theoretically this should be the solution, but the problem is, that the wizard config ;;wizards[tx_wizards_uploads_path] is not respected for some reason

t3lib_div::loadTCA('tt_content');

$TCA['tt_content']['columns']['select_key']['config']['wizards']['tx_wizards_uploads_path'] = array(
    'type' => 'popup',
    'enableByTypeConfig' => 1,
    'title' => 'Link',
    'icon' => 'link_popup.gif',
    'script' => 'browse_links.php?mode=wizard&act=folder',
    'JSopenParams' => 'height=300,width=500,status=0,menubar=0,scrollbars=1',
    'params' => array (
        'blindLinkOptions' => 'page,mail,url,file'
    )
);

$TCA['tt_content']['palettes']['uploads']['showitem'] = str_replace(
    'select_key;LLL:EXT:cms/locallang_ttc.xml:select_key.ALT.uploads_formlabel',
    'select_key;LLL:EXT:cms/locallang_ttc.xml:select_key.ALT.uploads_formlabel;;wizards[tx_wizards_uploads_path]',
    $TCA['tt_content']['palettes']['uploads']['showitem']
);

This is working, as the field gots moved from the palette to the root type level ;)

if (!defined('TYPO3_MODE')) {
    die ('Access denied.');
}
t3lib_div::loadTCA('tt_content');

$TCA['tt_content']['columns']['select_key']['config']['wizards']['tx_wizards_uploads_path'] = array(
    'type' => 'popup',
    'enableByTypeConfig' => 0,
    'title' => 'Link',
    'icon' => 'link_popup.gif',
    'script' => 'browse_links.php?mode=wizard&act=folder',
    'JSopenParams' => 'height=300,width=500,status=0,menubar=0,scrollbars=1',
    'params' => array (
        'blindLinkOptions' => 'page,mail,url,file'
    )
);

$TCA['tt_content']['palettes']['uploads']['showitem'] = str_replace(
    'select_key;LLL:EXT:cms/locallang_ttc.xml:select_key.ALT.uploads_formlabel,',
    '',
    $TCA['tt_content']['palettes']['uploads']['showitem']
);
$TCA['tt_content']['types']['uploads']['showitem'] = str_replace(
    '--palette--;LLL:EXT:cms/locallang_ttc.xml:media;uploads',
    'select_key;LLL:EXT:cms/locallang_ttc.xml:select_key.ALT.uploads_formlabel;;wizards[tx_wizards_uploads_path], --palette--;LLL:EXT:cms/locallang_ttc.xml:media;uploads',
    $TCA['tt_content']['types']['uploads']['showitem']
);

Thanks Kay,
I can confirm that your solution is working.