[NTG-context] Showing parts of PDF files or splitting PDF files

Hi, I need to include a PDF picture in a ConTeXt document that is much too detailed to be scaled down onto a single page. So I need to distribute it across two ore more pages. - Is there a way to display only a part of a PDF file in ConTeXt, like it could be done with manipulation of the bounding box of a PostScript picture in LaTeX? - Does anyone know an application that will split a PDF file into user-defined parts (not just printing pages)? - Any other ideas? Ciao, Matthias