What do u mean by connecting… IS 7.x from 6.5, if u say only remote connection or through remote connection alias yes you will be able to connection ( it will just be any other connection from http client) and you can remotely invoke services etc.
but if u are looking for connection and use some components from other version, its not supported. like you want login using 7.X developer to 6.x IS or vice versa.
-nD
#Flow-and-Java-services#webMethods#Integration-Server-and-ESB