It is possible to make any links on a menu created with the Menus system in Wordpress open in a new window. You can use the Wordpress menus system to create menus for the sales pages, squeeze pages, launch pages, blog pages and membership pages in OptimizePress.
Follow these steps:
When viewing the menu administration page, click on Screen Options (top right), and check the box labelled Link Target under the Show advanced menu properties heading.
Now select a link item you have created for your menu and you will see the option to select the target for your custom link.