overly long lines in pdf output of manual from package

In re-factoring my optimx package, I'm finding that the pdf output has some lines that are
outside the margins (and there are warnings in R CMD check optimx). Clearly I can fix this
by editing the tex file that is generated, but the build infrastructure would still get
things wrong in automatic processing. So that gives rise to 3 questions:

1) How do I adjust the DESCRIPTION file to avoid too long a line (optimx uses a lot of
other packages). I can add \cr elements to the Rd files to control those lines, but
DESCRIPTION doesn't allow this.

2) Is there an option control that does the job? I've not found one 
in searching, but could easily have chosen poor search terms.

3) To avoid running the whole of R CMD check to rebuild the manual, 
do I need to dig into R CMD check to find the bits that just build 
the manual, or is there an option to Rd2pdf to do this? I've found 
how to process a list of files with Rd2pdf, but need to add the 
DESCRIPTION stuff.

Best

John Nash