Youre on the right track though construction script is the way to have things changeable during level or layout design.
Ok so quick step through this process.
- drag your scenecapture or any component in to the construction script and click on GET.
- drag off that node and for this example start typing SET and then select Set TextureTarget
- right click on the drop down in the texture target and choose promote to variable
- at this point you should have a variable of the right type which you can name whatever you like then CHECK the box that says EDITABLE.
now if you drag this into your level you will see in its detail panel a way to change it value and if you have more than just one each one can have a different value.