Well… if you are asking if you can get the List category posts plugin to recognize the tag then you can use the “get_extended()” function in WordPress.
Create a new List category template and then use the following code to get the part of the post before the more tag for display.
$moreTag = get_extended($single->post_content);
$beforeMore = $moreTag['main'];
If you are interested I am creating a List category template for use with the TwentyTen theme – specifically for use with a page template that will be used to display WordPress pages in custom Facebook tabs. Let me know and I’ll get it to you.