You could do that with a wildcard Find/Replace, where:
Find = ([\{]{1,})([!\}]@)([\}]{1,})
Replace = \2
or even:
Find = [\{]{1,}([!\}]@)[\}]{1,}
Replace = \1
and the replacement font is specified as italic (though I'm not sure what you mean by "from roman to italics", since Roman is a font name and italics is a font attribute that can apply to the Roman font).

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]