Hm, by default such feature doesn't supported but it can be implemented with some modification of JComments Content plugin. At this moment comments list is displayed using onAfterDisplayContent method but you need make some changes... Something like this (I didn't make any tests but it must work)
1. Open /plugins/content/jcomments.php
2. Find and replace line:
function onAfterDisplayContent(&$article, &$params, $limitstart = 0)
with
function displayComments(&$article, &$params, $limitstart = 0)
3. Find and replace
} else {
JCommentsContentPluginHelper::clear($article, true);
}
with
} else {
if (JCommentsContentPluginHelper::_findTag($article, '/{jcomments}/is')) {
$commentsList = $this->displayComments($article, &$params, $limitstart);
$article->text = str_replace('{jcomments}', $commentsList, $article->text);
}
JCommentsContentPluginHelper::clear($article, true);
}
So after this you can insert into text tag {jcomments} and it will be replaced with comments list, i.e. you can insert comments inside article text.