Thanks for the tip, but now it seems I'm getting another error message. The same is true when I try with Michael's method, I get the same error message about NAMESPACE then as well. Any ideas?
> library(devtools)
> install_url('http://rock.icr.ac.uk/software/shrnaseq/shRNAseq_0.3.tar.gz')
Downloading shRNAseq_0.3.tar.gz from http://rock.icr.ac.uk/software/shrnaseq/shRNAseq_0.3.tar.gz
Installing package from /tmp/RtmpeF1G84/shRNAseq_0.3.tar.gz
Installing shRNAseq
'/usr/lib/R/bin/R' --vanilla CMD INSTALL '/tmp/RtmpeF1G84/shRNAseq' \
--library='/usr/local/lib/R/site-library' --with-keep.source \
--install-tests
* installing *source* package 'shRNAseq' ...
ERROR: a 'NAMESPACE' file is required
* removing '/usr/local/lib/R/site-library/shRNAseq'
Error: Command failed (1)
>