i'm sorry to say there is a art to it, it can only be done from the front via the port hole, i would put washing up liquid round the rim of the new door seal where it goes on appliance, get your hands in and lip it on and all the way round until its pops on and the internal spring/restaint band is a little more fun, cross your hand over upside down start at the top and go for it, i always put a long screw driver thro the interlock to hold the spring from moving, holding it by somebody else or my knee, then hold while pushing the spring into the grove, one in the plastic clip on front is easy.
I'm sorry to say its not a easy job, but it can be done
foot, July 2009