If you already have a DataValet password/id from your stays at Hilton etc. then you can just use that. Don't need to create a new account for MLL.
Just opening the internet browser doesn't open DataValet log in screen for me though (perhaps because I have an https, rather than http, site as my opening page). When I switch to a non https site, e.g. aircanada.ca, then the Data Valet log in screen appears. For those of you who may have had trouble getting logged on . . .