There is one <param that deals with rotation speed called Auto.  Typically when specifying Auto.. it is only for the first viewing the image.  You may assign this rotation speed in PtViewer Scripter.

When you mouse over and stop the rotation then you click on the < and > buttons on the tool bar ANOTHER command issues the rotation speed.

I think what you are talking about is the speed control when clicking on the left or right arrow on the tool bar.  These are your Shotspot commands.

My shotspot code strings are oriented left to right across the toolbar.  So my shotspot0  is for the < arrow.  Shotspot1 is for the > arrow.

Sample shotspot:

<PARAM name = shotspot0 value = " x291 y227 a311 b247 u'ptviewer:startAutoPan(-0.2,0,1.0)' ">

Notice the 3 values in parenthesis -> startAutoPan(-0.2,0,1.0)

The first value -0.2 is for the speed of 2/10ths of a degree per second and is showing a minus number for turning LEFT.  A positive number is rotate to the right 2/10ths of a degree per second to the RIGHT.

You would want to assign a 0.2  or 0.3  to shotspot0 and shotspot1.

Hope that helps

Dave