I had tried getting wkhtmltopdf working a few months ago; however, I was unable to get it working. Seemed to be a problem at the Drupal integration level since wkhtmltopdf worked at the command line level. I was curious whether you had to do any specific tweaking to get wkhtmltopdf working with Drupal (e.g. had to use specific version of wkhtmltopdf, etc.)?