FullText user interface with PHP

Right now on a form I have the instructions below, the mysql FullText
search works nicely when done manually w/these instructions.

I'm thinking of replacing the text the user sees below with some
self-explainatory radio buttons. Can I just put (using PHP processing )
"+" in front of each word submitted in a search field by the user if
"all words"radio button is checked ?. Or if the radio button "phrase"
was checked, then simply put quotes around what the user submits? Is
there a better way? Snippet appreciated. Thanks.

FullText search instructions:
+ The word is mandatory in all rows returned.

- The word cannot appear in any row returned.

() Used to group words into subexpressions.

* The wildcard, indicating zero or more characters. It can only appear
at the end of a word.

" Anything enclosed in the double quotes is taken as a whole (so you
can match phrases, for example)