Put it in your bathtub. Get yourself a reciprocating saw if you don't already have one. Start cutting it into manageable pieces, under 6 inches wide. Now, this next part sounds harder than it is.
Grab a long hose and drag it indoors. Unscrew the bolts holding your toilet to the floor, and remove the toilet. This is now the largest portal in your house leading to the sewer system. Feed the parts down that hole one at a time, covering them with water from the hose to aid in "flushing" them. Give enough time for them to disappear down the hole before putting the next one in. It will take a while but all the parts should be gone by now.
Get some bleach if you don't have any, and thoroughly clean the tub and the floor between the tub and toilet.