No, Silverlight is designed from the ground up to be completely sandboxed, no way to bypasss that (thank god).
If you need that kind of access, but are looking for an easy deployment, I would suggest building a Clickonce application.
There are restrictions, because I think by default they are not full trust, but that's the best you will get.
It's also going to be the only easy route if you need printing (unless you are willing to round-trip to a server to generate a PDF file).
If you need direct access to some hardware (like for a POS software with cash drawer, receipt printer etc), you need to go "desktop". Clickonce can give you some deployment options, XBAPs can give you the "browser experience", but you are going to have to make compromises based on what your "hardware access needs" are.