There are a few ways and hacks to do this (not going to discuss that here), but what you should know is that none of them is perfect and fault-free. There is another problem with custom fonts, and that is embedding them into your presentations. A presentation with Arial can look better than some overly-designed presentations with their fancy-schmancy custom fonts.
A good designer should be able to work with these fonts just as they would have to work with a customer’s CI font. While the standard way in which PowerPoint displays ‘system’ fonts might be perceived as boring, it would be cheap to say your presentation will always look bad if you use Arial or Times New Roman. You may have heard people say “System fonts are boring!”, “System fonts suck!” and “Never use system fonts again!”.