Workaround for Paazl Parcelshipper

To allow Fooman Pdf Customiser to provide the packing slip pdf: Open the following file: app/code/community/Paazl/Parcelshipper/etc/config.xml

and change 

<order_pdf_shipment>Parcelshipper_Paazl_Model_Order_Pdf_Shipment</order_pdf_shipment>

into

<!--order_pdf_shipment>Parcelshipper_Paazl_Model_Order_Pdf_Shipment</order_pdf_shipment-->

Save the file and refresh Magento's cache.

This allows Pdf Customiser to supply the packing slip. To include the Paazl information go to System > Configuration > PDF Print-outs > Pdf Customiser by Fooman.

To add the preferred delivery date, put

{{block type="paazl/fooman_pdfCustomiser_preferredDate"}}

in the Store Address field.

To add a shipping label, put

{{block type="paazl/fooman_pdfCustomiser_label" rotate="rotate" x="105" y="2"}}

in the Custom Text field under the Shipment header. As you might have noticed, this tag contains the parameters rotate, x and y. Using these parameters, users can customize orientation and positioning of their label. Omitting the rotate parameter will cause Paazl to no longer rotate the label by 90 degrees. The x and y parameters correspond to the offset, in millimeters, of the bottom-left corner of the label to the bottom-left corner of the page. The label height and width can be adjusted in app/code/local/Parcelshipper/Paazl/Block/Fooman/PdfCustomiser/Label.php.

Note on Magento 1.9.2.2 version and later:

You need to add the block names

paazl/fooman_pdfCustomiser_preferredDate
paazl/fooman_pdfCustomiser_label

in System > Permissions > Blocks and set these as 'Allowed'.