Use this command, replacing the "insertcommandhere" and "insertothercommandhere" with your two commands.
Command:
/summon FallingSand ~ ~1.6 ~ {TileID:152,Time:1,Riding:{id: FallingSand,TileID:137,Time:1,TileEntityData:{Command:/insertcommandhere},Riding:{id:FallingSand,Time:1,TileID:152,Riding:{id:FallingSand,TileID:137,Time:1,TileEntityData:{Command:/insertothercommandhere}}}}}
Note: The insertothercommandhere goes off first.