In Dataset Explorer copy the slab part to your project dataset, rename it with the suffix _Insulation.
In the Cut Patterns definition:
In DataGroup Explorer:
The new slab should show up in the available slabs when you start the place slab tool, if not click the Refresh library icon in the tool.
The pattern can't interactively re-flood/scale to fill the slab depth so if you get the pattern size right for a particular slab depth it will be cropped for thinner slabs or will repeat for thicker slabs.
The options for dealing with this are:
This example is a 150mm slab using the GB Dataset and the 'baten' pattern:
and with the 'honey' pattern: