[Rcpp-devel] Installing my own package in the system directory

Hi,
I use an Intel desktop under Ubuntu 11.04, and I have super-user
privileges. I wrote a utility i/o function to use in R. I am able to
install it in my account's R/site-library, and it works fine.  I
cannot install it on the system R/site-library using either R CMD
INSTALL or install.packages; I get an "invalid package" warning
followed by an "Error: ERROR: no package specified", etc. All of that
goes away if I specify to install in my account's site library. I read
about setting up a local repository, but before I plunge into setting
something like that for little things, I'd like to know I haven't
missed something obvious.  Is there something else I may do?
Best,
Mario