Impey Wetgaurd over lip/shoulder

[GlanMenai]

Hello,

 

I'm just about to install the impey wetguard membrane over our impey linear shower tray, but I'm not sure how to install it over the little lip/shoulder that's on the side of the tray? 

 

I've watched countless installation videos on the subject but non of them installs the membrane over the linear dec (usually on the death star one).

 

Has anyone got any advice on how to take into account that little lip/shoulder? Do I push the membrane onto the lip and form the two 90 degrees up from the shower tray and then 90 degrees out again to the floor level over a few mm to get it tight in there? 

 

Thanks!