In your theme, you need to find calls to next_posts_link() and previous_posts_link() and replace them.
In the Twentyten theme, it looks like this:
Codice PHP:
<div class="nav-previous"><?php next_posts_link( __( '<span class="meta-nav">←</span> Older posts', 'twentyten' ) ); ?></div>
<div class="nav-next"><?php previous_posts_link( __( 'Newer posts <span class="meta-nav">→</span>', 'twentyten' ) ); ?></div>
You would replace those two lines with this:
Codice PHP:
<?php wp_pagenavi(); ?>
For multipart pages, you would look for code like this:
Codice PHP:
<?php wp_link_pages( ... ); ?>
and replace it with this:
Codice PHP:
<?php wp_pagenavi( array( 'type' => 'multipart' ) ); ?>
Go to WP-Admin -> Settings -> PageNavi for configuration.