SQL & PL/SQL

I had an insert script with data strings having '&' character. While executing it on sqlplus it prompted for a value at each occurrence of '&' .

Simple solution was to put a "SET DEFINE OFF" at the beginning of the script. It suppressed the prompt for value.

However, it left me with a question. What if my insert script require both things...
1. Insert data strings having '&' character.
2. Prompt for a value at few places.

How would I achieve that?

Thanks for your inputs.

--Rob