NEW YORK (AP) _ Louis Dell'Olio, designer became Louis Dell'Olio, ''soap star'' recently when a crew of the long-running daytime drama ''Search For Tomorrow,'' filmed shots at his spring-summer preview.

The experience may have awakened some long-hidden desires for Dell'Olio who said afterward, ''I've always wanted to be an actor.''

The scenes shot at the Anne Klein showroom on Seventh Avenue will be aired the week of Dec. 2 and Dell'Olio will tape a second segment at the NBC-TV studio on Nov. 21. The latter will air the week of Dec. 16.

In addition to giving millions of soap fans an inside look at the hurlyburly world of fashion, the scenes will be incorporated into the current storyline.

When the lights dimmed in the showroom two added guests were Search characters Liza Sentell (actress Louan Gideon) and her daughter T.J. (Jane Krakowski). The pair traveled from the fictional town of Henderson to the Big Apple to try and save the widow Sentell's ailing empire.

All in all, Dell'Olio had it pretty easy - he got to play himself. Liza and T.J. (and the five-man crew) were invited backstage before the real fashion show got under way to get a firsthand look at the spring line and watch the models applying their makeup.

But Dell'Olio wasn't the only one thrilled by the experience.

''I've never been to a fashion show in my life,'' enthused the 16-year-old Krakowski. Miss Gideon was a bit more reserved but admitted it was exciting to tape outside the studio. ''It brings a lot of verve to the show.''

Dell'Olio, a veteran of the Donahue show, said he agreed to do the guest shots ''for fun. It's not something I do every day and I like to try new things.''

Besides, he wasn't a bit nervous when the cameras started rolling. ''With all those writers and buyers sitting in the audience the only thing I was worried about was if they would like my collection.''