If it's French, then it's like dooj but with a 'soft' j -
it's sort of halfway between English j and sh, sometimes rendered as 'zh'.
You can also try imagining that the English j sound is really 'dj', and then try to drop the d sound from it...
There is always the chance that Mr B.L. d'Ooge americanised the pronunciation of his name to something like "dooj", but the Dutch pronunciation (courtesy of Mr Miek-de Vos of the Dutch Embassy) is as follows:
Dough - ch - u
Dough (as in bread) - ch (as in loch in Scotland) - u (as in surname)