Overriding default text of \f, \p, etc.

[YTG 1234]

Hello List,

I want to override the default text markup used with commands such as 
\f, \p, \mf, etc.

However, trying to define f = #(make-dynamic-script ...) doesn't work 
because Lilypond interprets f as a note-name.

Additionally, how would I be able to change the text while maintaining 
the MIDI effect? I tried using \tweak DynamicText.text but it doesn't 
seem to override the text...