[CMake] Is there a way to tell cmake to only care about certain targets?

[cheshirekow]

I'm trying to automate generation of doxygen documentation for codes on
a webserver. The webserver contains a working copy of the codes checked
out from version control, and I'd like to script the process of going
into each and running doxygen. The server that's running the site
doesn't have all the libraries necessary to build all the codes that I'd
like to generate the doxygen for (and it's unreasonable to install all
the libraries for all the codes by everyone in our group, just to
generate the documentation). 

Is there a way to tell cmake to only care about the doc target? As in
don't fail when it can't find libraries required by other targets?

This question on the FAQ *sounds* like my question:
http://www.vtk.org/Wiki/CMake_FAQ#Is_there_a_way_to_skip_checking_of_dependent_libraries_when_compiling.3F
but it assumes the makefiles are already generated. If cmake fails
because required libraries are missing, the makefiles wont get
generated. 

Any help would be appreciated.