[Farhoof]

Switch to volume trim view, drag volume trim down. These angles will be 90deg but you can grab the lowered breakpoints and move them inward to create a slope (or cmd+click on the lowered portion of the line to create a new breakpoint and alt+click on the 90deg breakpoint to remove it so the 0dB breakpoint will connect to the newly created one).
When done, select the track and 'coalesce volume trim automation'.

Or consider a S1 fader box and ride the volume trim by hand, same effect but faster.