I did some test on generating pdf's of Acclaim slides
without cl-pdf hacking. If you do just screenshots, convert them to
ps, concatenate these files and convert the resulting ps to pdf, you
get a quite usable pdf with a reasonable size, of course only if you
don't use a background picture (just call (setf
acclaim::*show-bg-image* nil)). I got a 223068 bytes file for 10 pages.
I think that this is okay. Here is the recipe:

- Install scrot (apt-get install scrot on debian, else go to
  http://linuxbrit.co.uk/scrot/),
- add this near the end of acclaim.lisp (i.e. just before (t nil)):

  (#\s (sb-ext:run-program "/usr/bin/scrot"
          (list (format nil "~a/slide-~3,'0d.pnm"
               "/home/mgr/daten/coding/lisp/acclaim/pdf/tmp"
                        number)))
        nil)

  (modifying of course the specified path),
- call (acclaim:start) and press #\s (as in screenshot) for each slide,
- open up a terminal and go the the specified directory and
  fire up something like the following (in bash):

  for i in slide*pnm; do pnmtops $i ; done | ps2pdf - > slides.pdf

- Voila.

Perhaps this is not as elegant as using cl-pdf, but at least the pdf
will look exactly like the Acclaim slides..

---
errata:

Use something like

for i in slide-*.pnm; do \
   pnmtops -dpi 75 -scale=1.0 -width 16 -setpage $i ; \
done | ps2pdf14 - > all-tmp.pdf; pdfopt all-tmp.pdf all.pdf

instead. This makes a non-scaled version of the slides (without
changing the file size), with perhaps a slightly better pdf because of
the pdfopt. The value of width=16 resembles my screen width of
1152 pixels (calculation: (ceiling (/ 1152 75))). This results in a
385 kB PDF for Christophe's slides (without background image, if he used
one anyway).