Hi Wittloc,

You can use Insert Hyperlink/ Action to do this.

Using Action
Select your text box/ shape.
Insert Tab
Action button (in Links group)
Select Hyperlink to
Select "Slide...."
Select Slide to link to
Click OK.

Using Hyperlink
Select your text box/ shape.
Insert Tab
Hyperlink button (in Links group)
Select "Place in this document"
Select Slide to link to
Click OK.