The wkhtmltopdf 0.9.6 Manual documents this parameter :
--page-height <unitreal> Page height (default unit millimeter)
Therefore defining an enormously long page can be done via :
which both define a page of height of 100 meters
(I mention both in case your wkhtmltopdf does not support
wkhtmltopdf, I do not know if there is some upper limit to
page-height, but you can find that empirically.
In addition you can try to add
--disable-smart-width (width is not an error) and try for the moment the less ambitious
In this man page there is a comment about
disable-smart-width that it's only available using patched QT.
There is also another comment:
On the wkhtmltopdf website you can download a static version of wkhtmltopdf at http://code.google.com/p/wkhtmltopdf/downloads/list. This static binary will work on most systems and comes with a build in patched QT.
The project has moved elsewhere, so you might hunt there for such a version, or ask in the forums.