Dunklian Was a gibberish language made by hero official (channel terminated).
1) this language sounded like some kinda icelandic/norwegian/finnish dialects all together.
2) There was only one dialect for the language (Northern Dunklian).
3) This langauge was only used in some fandubs of some clips of Phineas and Ferb.
There is no actual way to speak Dunklian.
You just have to use your Imagination.