What starting point do you have? Do you have the Report Generation Toolkit? There is no pre-made VI for this, so you'll have to manipulate the ActiveX reference using property nodes and invoke nodes to perform the actions.
If you have the Report Gen Toolkit, you can use the Word Get ActiveX References to get the "_Document" reference. Once you have that, there's a stupid simple Password property that you can set. Blank input gets rid of the password protection. There is also an Invoke method called Protect, which can set specific document protection options.
