XF 1.5 How do you edit the PageNav?

[Blast]

This is the code:

<xen:pagenav link="forums" linkdata="{$forum}" linkparams="{$pageNavParams}" page="{$page}" perpage="{$threadsPerPage}" total="{$totalThreads}" />

I want to add 1-2 span classes in there so I can control the Next and Previous buttons.