Use atlas name in string?

[LudiusMaximus]

Looking at the global strings I have figured out that you can use textures in strings like this:

"|TInterface\\OptionsFrame\\UI-OptionsFrame-NewFeatureIcon:0:0:0:-1|t" .. "My label text"

This works for me, but how can I do this with Atlas names?
When I try to emulate global strings like this,

"{Atlas|NPE_RightClick:20}" .. "My label text"

I get:

{Atlas
PE_RightClick:20}My label text

I am using the string as the "name" attribute of an AceConfig-3.0 "execute" button.