There we go, it's finally available to buy :
[url]http://www.forgeworld.co.uk/New_Stuff/CERASTUS_KNIGHT-LANCER.html[/url]
"Rules for using the Knight-Lancer in games of Warhammer 40,000 can be found" :
[url]http://www.forgeworld.co.uk/Downloads/Product/PDF/L/lancer.pdf[/url]