If your shortcode is something like
[wppa type="slide" album="19"][/wppa]
( or maybe type="slideonly"
or type="slideonlyf"
) and it is the first wppa shortcode on the page, use the text editor (not the visual) and add a scriptline as follows:
[wppa type="slide" album="19"][/wppa]
<script type="text/javascript">_wppaTimeOut[1]=1000;</script>
This sets the slideshow timeout for the first shorcode ( _wppaTimeOut[1] ) to 1000 milliseconds.
Second shortcode 1500 ms would be:
<script type="text/javascript">_wppaTimeOut[2]=1500;</script>
Important: the script must be placed AFTER the shortcode, and this will only work on a page (a post is not always the first on a page) with a slideshow shortcode. If you display thumbnails that link to slideshow, it will only work when using ajax is switched off (not recommended)