[Rd] R CMD check and interfacing packages

[Gabor Grothendieck]

For an R package whose purpose is to interface to other software,
since such other software is not necessarily being on CRAN how does one 
proceed so that the R package can pass 'R CMD check'?  None 
of the examples or demos in the package can run without the software 
being interfaced to.

Is there an example of such a package that could be used as a 
prototype?

Thanks.