🚀 go-pugleaf

First, you need to use fonts that support Hungarian characters. Your Mac system fonts may, and all the OpenType "Pro" fonts that came with InDesign 2 do as well (Adobe Caslon Pro, Adobe Garamond Pro, Caflisch Script Pro). 

You can't directly type Hungarian with a US keyboard layout. Not possible. You need to switch to a Hungarian keyboard to access this character, or manually paste it in. 

I'm not sure whether switching to a Hungarian keyboard will work with InDesign directly, but in a worst case you could type in Hungarian in your text editor and save a Unicode text file (assuming your text editor supports Unicode). You can then import that into InDesign. 

For small amounts of text with just a few special characters, you can also use InDesign's "Insert Glyph" function to get at any character in any font. 

Regards, 

T