you can do this quite easily, if you are on the slide you want to change go
to format and then down to slide design, you can then choose a design from
the list but instead of just clicking it, select the design and an arrow will
appear on the right hand side of it - a drop down menu will then appear and
you can choose to apply the design just to the slide you have selected. if
you are wanting 5 slides to have this design but you want the rest of the
presentation to have a different design just select the 5 slides that you
want to change and choose apply to selected slides.
if you dont want to use one of the pre made designs, you can create your
own, if you go to view and then master you can create a second master slide
with your own individual design on it... then when you go to format and sldie
design your desing will be an option to select from and you can apply it to
as many slides as you want in the same way.
hope this helps
