how to insert a block within a cck input form in Drupal 7?
So you're block is created and working?  You just want to insert it as a field?  You can do that using Display Suite, or if you want to insert it within a text field you could try Insert Block (still in dev)

I think Display Suite is the way to go, it is a very comprehensive module so it takes time to take it all in, but it provides very intuitive solutions for Drupal shortcomings, such as displaying a block as if it were a field.