What I did on my most recent tomcat "install"
-unpack tarball
-move to bin directory
-type startup.sh
-see error message about JAVA_HOME and JRE_HOME
-set JAVA_HOME and JRE_HOME
-startup
-profit
Obviously that was on linux but it shouldn't be any different on windows (you could dig into startup.sh and startup.bat if you want to see if there are any differences). Probably all you need to do is set one of those env variables, or CATALINA_HOME, like bunker said, although I believe it defaults to ".." (one above the bin directory) if you don't. You have to be careful if you do set CATALINA_HOME and then try to do a parallel install without changing the version. Even though you run startup in the new bin directory it'll fire up the old version which can be a little confusing
