http://www.ecf.com/14_1 - you can buy German/English route guides here. You'll be wanting Route 2, I guess.

I've done Hook of Holland to Cologne - generally the route was very clearly marked, only a couple of misroutes (I accidentally found myself in Belgium at one point!). If you had a hiking GPS pre-set with the waypoints it would be very easy.

One thing that's odd - very surprised that Eurovelo doesn't have everything on a Google Map and with a full pack of downloadable waypoints. They're surely not attempting to protect their map sales are they?