I have a van that I have already changed the tranny seal on but because I forced the seal it still leaks. Any tips on how to install transmission seal for a 1997 plymouth grandvoyager?

Did you torque it down properly?

Changing and flushing automatic transmission fluid (http://www.allpar.com/eek/atf.html)

I have a van that I have already changed the tranny seal on but because I forced the seal it still leaks. Any tips on how to install transmission seal for a 1997 plymouth grandvoyager?
Which seal are you referring to? There are several different seals and different install concerns with each.