From the front panel, press the Fast Forward (>>) or Fast Backward (<<) buttons to change the tempo while a song is in play.

From the remote control, press Right key(>) or Left key(<) while a song is in play.

From the remote control, press Subtitle key or Angle key to change the tempo before a song is in play.

Note that at the end of each song, the tempo control will be reset. 

All above is also same for DVD-105G, 203G, 305G or their USB versions.