Custom options for dependent systems

Hi all, I have a following problem. I'm defining a system which depends on cl-charms. cl-charms in its turn contains some cff-groveller file. But this file could not be compiled unless I provide cc-flags to the include directory. So the question is how to define dependency on cl-charms in my system providing some argument which will be used while compliling/loading cl-charms, like the variable containing cc-flags? Br, /Alexey