3TB MyBook Permissions problem

When plugged straight into my iMac I can write to this drive, however when I plug it into a media player on my network it will no longer allow me to write files from my iMac (even though I can see it in Finder).

I’m assuming it’s a permissions issue - but I’m running Mountain Lion so can’t use Smartware (to my knowledge) as it’s not currently supported, so how do I change it to allow me to write to it whether I’m hard-wired over usb or not?

A friend told me to go into terminal and type the following:

sudo chmod 777 /Volumes/MyBook     (the later part is the drive name)

this would supposedly open all permissions - but no luck.

Any help/insight would be much appreciated, this is very frustrating…


Quick update - I just realized there is an update for Smartware that works with Mountain Lion!

Problem is, I see nothing in Smartware that allows me to change any permissions that would allow me to write to this drive over my network… any ideas?