Category Template Modify help needed

You can modify the number of posts displayed per page on a per-template basis using query_posts.

http://codex.wordpress.org/Template_Tags/query_posts

If you have the number of posts per page set to 10 but want to show 50 posts on your category page, you would need to edit (or create) your category template file (category.php) and add:

<?php query_posts('showposts=50');?>

immediately before:

if ( have_posts() ) : while ( have_posts() ) : the_post();

in that file.