Tall Pixel demonstrates a way to stretch still images vertically by a factor of 3/2, using mixed $2006/$2005 writes and timed code, so that the CHR data for your cut scenes takes 33% less space.

Tested on FCEU Karmic and on an NTSC NES + PowerPak.

http://nesdev.parodius.com/bbs/viewtopic.php?t=5822