The only way to do that is with a correlated subquery. There is some discussion and an example given here, in case you want to try hacking the plugin code:
http://www.ambrosite.com/plugins/next-previous-post-link-plus-for-wordpress#comment-9523
I like the plugin too!!
I am having a little trouble getting it to work in a single taxonomie.
see bottom of page for links
http://geoconinc.com.s157459.gridserver.com/projects/land-development-ld01/
using project type: Land Development
post type: projects
taxonomie
name: projecttype
slug: ptype
here is the code I am using
<div id="port-nav"><div id="poject-lft"><?php next_post_link_plus( array('in_same_tax' => true, 'link' => 'back project' ) ); ?></div>
<div id="poject-rt"><?php previous_post_link_plus( array('in_same_tax' => true, 'link' => 'next project' ) ); ?></div>
thanks for anyones suggestions.
jD
Is your custom taxonomy set up as hierarchical or non-hierarchical? The plugin only works with hierarchical taxonomies.