Is it possible to create more complex conditions in Eloqua 9 forms processing steps using boolean logic in search builder?

When setting up a conditional processing step, is it possible to create more complex conditions in Eloqua 9 using boolean logic in search builder?
I would like to set up a condition like this: field value "IS NOT 'something' OR empty".
The Eloqua 9 forms processing steps manual only mentions use of wildcards * and ?.