Well, I know the required hyperlink of Slideshow window (id=2007).Logic is basically the same, just get the ID from the slideshow.xml file and use it for hyperlink #
The onright/onleft etc. refer to the ID of the button that you should jump to when press the arrow keys
<control>
<type>button</type>
<id>...</id>
<label>Slideshow</label>
<posX>...</posX>
<posY>...</posY>
<width>...</width>
<height>...</height>
[b]<hyperlink>2007</hyperlink>[/b]
<control>
<control>
<type>button</type>
<id>...</id>
<label>Slideshow</label>
[b]<action>XXXXXXX</action>[/b]
....
[b]<hyperlink>2007</hyperlink>[/b]
<control>
<control>
<description>SlideShow button</description>
<id>6</id>
<type>button</type>
<label>108</label>
<font>font12</font>
<posX>460</posX>
<posY>1</posY>
<height>10</height>
<width>200</width>
<textYOff>0</textYOff>
<onleft>8</onleft>
<onright>7</onright>
<onup>50</onup>
<ondown>50</ondown>
<textureFocus>-</textureFocus>
<textureNoFocus>-</textureNoFocus>
</control>
<control>
<type>button</type>
<id>...</id>
[b]<label>Switch to MyPictures</label>[/b]
....
[b]<hyperlink>2</hyperlink>[/b] <!-- It's a link to "MyPictures" window-->
<control>
...In the mean time you can put a saved playlist in the picture directory and it will start automatically when you start the slideshow. Just name it folder.m3u.
The setting in MP Configuration, Music settings will determine if the playlist is shuffled at startup.
You are right in common, but these particular plugins I tried last year and was unhappy because of bugs...use a fullscreen music visualization that displays slideshow images from your computer.