Please install the package in R directly using the commands:
install.packages("devtools")
::install_github("kbroman/regress") devtools
Clifford, D., & McCullagh, P. (2005). The regress function. The Newsletter of the R Project Volume 6/2, May 2006, 6. (link)
Forked from David Clifford, but now maintained by Karl Broman.