<!-- BEGIN TOPLIST -->
<CONFIG>attachments[,]time[,]1[,]descending[,]deleted=0 AND memberid={MEMBERID} AND (filetitle LIKE '%.jpg' OR filetitle LIKE '%.jpeg' OR filetitle LIKE '%.png' OR filetitle LIKE '%.gif')[,][,]0[,]0[,]0[,]1[,][,]0[,]0[,][,]0[,][,][,]</CONFIG>
<a href="{ATTACHSLIDEURL}" title="{ATTACHLABEL}" rel="lightbox[member{MEMBERID}attachments]" id="firstslide">Start {MEMBERNAME}'s Slideshow</a>
<!-- END TOPLIST -->
<div class="lightboxgallery" style="display: none; height: 0;">
<!-- BEGIN TOPLIST -->
<CONFIG>attachments[,]time[,]500[,]descending[,]deleted=0 AND memberid={MEMBERID} AND (filetitle LIKE '%.jpg' OR filetitle LIKE '%.jpeg' OR filetitle LIKE '%.png' OR filetitle LIKE '%.gif')[,][,]0[,]0[,]0[,]1[,][,]0[,]0[,][,]0[,][,][,]</CONFIG>
<IF {NUMBER} is greater than 1><a href="{ATTACHSLIDEURL}" title="{ATTACHLABEL}" rel="lightbox[member{MEMBERID}attachments]"></a></IF>
<!-- END TOPLIST -->
</div>
<CONFIG>attachments[,]time[,]1[,]descending[,]deleted=0 AND memberid={MEMBERID} AND (filetitle LIKE '%.jpg' OR filetitle LIKE '%.jpeg' OR filetitle LIKE '%.png' OR filetitle LIKE '%.gif')[,][,]0[,]0[,]0[,]1[,][,]0[,]0[,][,]0[,][,][,]</CONFIG>
<a href="{ATTACHSLIDEURL}" title="{ATTACHLABEL}" rel="lightbox[member{MEMBERID}attachments]" id="firstslide">Start {MEMBERNAME}'s Slideshow</a>
<!-- END TOPLIST -->
<div class="lightboxgallery" style="display: none; height: 0;">
<!-- BEGIN TOPLIST -->
<CONFIG>attachments[,]time[,]500[,]descending[,]deleted=0 AND memberid={MEMBERID} AND (filetitle LIKE '%.jpg' OR filetitle LIKE '%.jpeg' OR filetitle LIKE '%.png' OR filetitle LIKE '%.gif')[,][,]0[,]0[,]0[,]1[,][,]0[,]0[,][,]0[,][,][,]</CONFIG>
<IF {NUMBER} is greater than 1><a href="{ATTACHSLIDEURL}" title="{ATTACHLABEL}" rel="lightbox[member{MEMBERID}attachments]"></a></IF>
<!-- END TOPLIST -->
</div>
You can customize the "Start {MEMBERNAME}'s Slideshow" link as you like. If you want to have the slideshow launch by clicking on a 500x300 thumbnail of the first image, just replace Start {MEMBERNAME}'s Slideshow with <img src="{ATTACHTHUMBURL[500 <,> 300]}">
If you want to display all of the slideshow's thumbnails in advance to let the viewer launch it in the middle, delete style="display: none; height: 0;" and then change rel="lightbox[member{MEMBERID}attachments]"></a> to rel="lightbox[member{MEMBERID}attachments]">{ATTACHTHUMBURL}</a> (of course, with a member slideshow this could be a very large number of thumbnails so not normally recommended).
If you want to automatically launch the slideshow when the page loads, without waiting for a click, just go to Admin -> Themes -> Manage Templates -> "Additional Document Ready Function Content" and insert
$("#firstslide").click();
there to simulate a click as soon as the page is loaded.