If I download an \"package-name\".tar.gz file from CRAN website, gunzip and untar it into a custom directory, how do I load that package from within R? I cannot extract the
Try using Hadley Wickham's devtools package, which allows loading packages from a given directory:
library(devtools) # load package w/o installing load_all('/some/package/diR') # or invoke 'R CMD INSTALL' install('/some/package/diR')