The following shows control and an imagelist placed under (i.e., in the same column as) a poster, to show thumbnails of additional posters. That's not what you want, but shows the use of imagelist. I suppose you would set the height and width higher, and put it in a column wide enough to display six in a row. Poster and the controls would still have to exist, but could be made small and placed elsewhere.
<row>
<column>
   <poster autosize="true" stretch="true"/>
   </column>
   </row>
<row>
<column halign="left" imgctrlcol="true" width="50">
   <prevposterbtn/>
   <nextposterbtn/>
   <addposterbtn/>
</column>
<column>
   <imagelist valign="top" halign="left" cheight="100" cwidth="75" autosize="true" space="10">
   <border shape="none"/>
   <color>$CCDDEE</color>
   </imagelist>
</column>
</row>
An alternative would be to use the screenshots container...
<section>
   <color>$000000</color>
<row>
<column>
<screenshots cheight="450" autosize="true">
   <border shape="none"/>
   </screenshots>
   </column>
 </row>
 </section>