Have you tried the 60 day demo? It’s oddly impressive for English.
Thanks I will try
Dutch language is not supported. Only English and Japanese for now. However, knock yourself out trying to get a Dutch accent out of the English language. G g g g 
While it would probably be a pain, you could try entering your lyrics phonetically. There is a chart for the phonetic values in the manual, albeit only showing how they map to Japanese and English words to help understand what each phonetic value does.
Maybe native English speaking people don’t realise it but English phonetics are really far away from most other languages. It is an exotic sounding language.
It might be easier working with Japanese phonetics. Haven’t tried it yet.
Including the word “phonetics.” 
Having formally studied Spanish, German, and Russian, and, informally, a bit of French, I do appreciate this. On the other hand, part of what makes English so challenging, not only for people for whom it was not their first language, but for native English speakers, is the mixture of words that have origins in other languages with different pronunciation rules. In any case, my note above simply used the word “try”, and with the intention that, short of having what the OP wanted, it might (or might not) be better than nothing.
The difficulty I see there is that you’d first have to understand the Japanese characters and the pronunciation of words that go with them to make the Japanese phonetics chart anything beyond blind trial and error. Short of that, it would, at minimum, mean doing a lot of experimentation and probably building your own phonetics chart for the Dutch language (in this case or whatever non-English language a given user might be trying to emulate). My assumption was that a western European on this forum would be more likely to have familiarity with English than Japanese.
In either case, it looks to me like the underlying phonetic characters are likely the same but just used in different combinations. Whereas most of the examples in the English chart use a single phonetic letter, most of the examples in the Japanese chart combine multiple phonetic letters.
The “it might be a pain” comment was simply meant that it would be a lot more work than just typing Dutch words and having the software translate that to phonetics. (But that will also be needed with English words in cases where the same spelling can have different sounds, or if you want to try an emulate a different regional accent.) Of course, there has to be an underlying assumption that all the needed phonetics for a specific language are available. I know English doesn’t tend to have very close approximations to some sounds (e.g. some German vowels with umlauts), but perhaps the underlying phonetic dictionary does (be it singly or in combination)? I also remember that the early Vocaloids I’d tried felt like it had a (non-English speaker’s) accent, despite being based on British singers, so it will be interesting to try Omnivocal out when I get a chance to see if things have improved significantly since 2004. 
LOL. But that is really a case of spelling, not phonetics.
It also regards systems of writing as they relate to the sounds of language, which makes the spelling rather ironic