Normally, in order to expose an R function as a tool in a Galaxy instance, you need to manually create an XML file with information about the function, and modify an additional XML file. The new RGalaxy package in Bioconductor automates this process, pulling most of the necessary information from the R function itself and its manual page (you provide the remaining information as arguments to the Galaxy function).
Please note that the package is now available only in the development branch of Bioconductor. So to install it, you need to have R-2.15, and do the following:
source("http://bioconductor.org/biocLite.R") useDevel() biocLite("RGalaxy")