I seem to be able to do it like this:
- Select Pi
- Control-9 (create inline cell)
- convert to Input
- Cell > Convert To > StandardForm Display
For the text "to enter pi, type Pi", the cell expression should be something like this:
Cell[TextData[{
"To enter pi, type ",
Cell[BoxData["Pi"], "Input"]
}], "Text",
CellChangeTimes->{{3.716552891901293*^9, 3.716552931558848*^9}}]
I don't know whether there is a shorter way.
