I've lived in Henan provice for around 8 years and have never seen any texts for learners of the Henanese dialect. There are considerable variations in dialect within Henan between people from different cities and even different districts within the same city. I am able to understand much of what is spoken, but can't figure out which tones are being used because they are so inconsistent. So the only way I know of learning Henanese is to memorize the pronunciation of phrases.
Henanese is much closer to Mandarin than dialects like Cantonese, Wenzhounese, etc. That may explain the lack of teaching material.
I know of foreigners who have picked up the local dialect, but I'm more of a visual learner. It would be far more efficient to look at a written guide. Are there any such resources for Henanese or other Chinese dialects?