This article is intended for those with high knowledge of PHP, HTML, JavaScript and CSS.

You can achieve this through the template override technique. First of all, you need to read This KB Article before you do anything else.

For membership, it requires a little more tweaking. You need to copy default_form.php and plist.php from /components/com_rpl/addon_membership/views/ to the html folder of your template as explained in the other KB article. Then you need to open default_form.php located in the HTML folder of your template and modify it to include plist.php from the template override folder.

If you just want to show a styled text in the position of MEMBERSHIP_PACKAGE_COMMENT, you only need to modify default_form.php in the override folder and replace "<?php echo JTEXT::_("MEMBERSHIP_PACKAGE_COMMENT");?>" with what ever text you would like to have. Doing this customization will result in having that part shown for all languages. If you need it to display differently in different languages, you need to use some php codes to get the active language of Joomla and show your content based on that.