Hey Mat,
You shouldn't need to get into the /vmimages/tools-isoimages folder, although it does exist.
1) Go to any datastore your VM has access to (even local host datastores), and browse the datastore.
2) Create a new folder, name it something like ISOs.
3) Upload a file to that folder from the datastore browser and select that ISO.
4) Switch over to the permissions page on that datastore and make sure that user or group has permissions there.
They should be able to see the folder you created when browsing for datastore ISOs on the VM. If it doesn't initially show up, there should be a dropdown to datastores by "Look In" when they're browsing, and if permissions are right they'll see that folder with the ISO.
If it's not working still, could you upload a screen of what you see at the browse on the VM's CD drive when logged in as that user?
~Brandit
