Theoretically, yes, but it's much easier if they have one or the other.
My understanding is that InContextEditing (ICE) allows YOU to create editable pages in DW that clients can access for editing with any FTP software, FileZilla for example.
With ICE, apparently you create the pages and then declare what's editable. That keeps the integrity of the page (JS, CSS, etc) while your clients can go into the editable region(s) and update things like prices and dates or times or articles.
There's more information in their forums, accesible from the link above.