Here is past tense of nan shiyo^ to? 何しようとう? or "What are you doing" in Hakata ben.
What were you doing (right now)? 何しようったとう? Nan shiyotta to?
Another example often heard in the Hakata region might be -
doko ni ikiyo^ to? どこに往きようとう?
or "Where are you going?" and again in past tense this sentence would be doko ni ikiyo^tta to?
Now for formal Japanese this is appalling grammar so it is to be used only in congenial situations as you would have amongst good friends or family members. This wouldn't be casually said to a stranger or someone you just met.
Japanese Grammar conclusion by looking at today's examples
to^ is the question marker and could be substituted for the participle ka か.
