Thanks for trying to answer, but I am afraid you did not really understand the question:
As I wrote, I am aware of the many R packages to do GO enrichment. The problem is that all the ones I have found so far (and indeed, the one you linked) are for gene set enrichment. They require you to specify a set of interest, to compare with the full set.
I am looking for a package that implements one of the existing method to work on ranked list, where no set is specified.