I had an email from a person that attended my art journal class at the local library. She said that sometimes she had problems adding text after using acrylic paint. Apparently, some pens and markers will not write over a glossy surface. She also likes to use crayons.
I remembered her from the class, she was very much taken with the Spilling Open art journal book by Sabrina Ward Harrison.
From my research it looks like the one way to add handwriting is to use a ruling pen and fluid acrylics. They seem to be available at art and drafting supply stores and even craft and office supply stores.
I plan to see if I can pick up one this week and experiment with it.