NEWARK, N.J. (AP) _ If you want a chance to buy one of Kevork Hovnanian's newest condominiums, you'll have to watch a Jerry Lewis movie this Saturday.

All-night lines and a deluge of inquiries forced the Red Bank developer to come up with novel ways of giving buyers a fair crack at condos, so Hovnanian's company has decided to hold a telethon.

Hovnanian Enterprises Inc. paid $20,000 for the commercial time on WOR-TV's 3 p.m. broadcast of the Jerry Lewis film ''Hook, Line and Sinker,'' said Ara Hovnanian, the company's 26-year-old executive vice president.

The first 50 callers during each of four breaks will have the chance to buy one of the company's 260 $100,000 garden condominiums under construction in Lincoln Park, 25 miles west of New York City.

''The purpose is not to advertise. We've been trying to decide what is a fair way to sell the units,'' Hovnanian said Thursday.

''What's happened in the last year and a half or so is that people have been starting to camp out'' for the chance to buy a condo at a Hovnanian development, he said.

Hovnanian said that's been a problem for his company, which specializes in moderately priced condos and townhouses in the tight New Jersey housing market.

During one such camp-out two months ago, a pregnant woman in line went into labor. ''She wouldn't leave until she got an appointment,'' Hovnanian said.

She eventually got an apartment.

In October, the developer sponsored a raffle before 9,000 people at the Brendan Byrne Arena for 334 modestly priced condos in wealthy Somerset County.

''This time, we had even more response than (for) that project. We said, 'Hey, this is crazy,''' Hovnanian said.

He said 7,800 inquiries for the Lincoln Park homes have come in over the past week. ''We get them now a hundred a day,'' he said. The company decided that the condo telethon gave prospective buyers an equal chance and was easier than renting a stadium.

''This way they can sit home all afternoon and all they have to do is try to call,'' Hovnanian said.

Only New Jersey residents are eligible to buy because Hovnanian lacks the registration credentials to sell New Jersey property to people outside the state.

A computer at the telemarketing center hired to take the calls can judge the order they are received by the millisecond.

During the three-minute breaks, representatives will explain the rules of the selection process and show photographs of the two-bedroom, two-bathroom homes.

''If you're any one of the first 200, you'll be guaranteed an apartment,'' providing mortgage requirements are met, Hovnanian said.

James Barry, vice president for sales and marketing, said the total $40,000 cost of putting on the telethon was less than a normal advertising campaign.

And if prospective buyers don't have a television?

''I think many public facilities do. What if you had to go to the Byrne Arena and didn't have a car?''

Lincoln Park, a bedroom community, is a quiet suburb of 9,000 people. Most of its residents commute to New York or the nearby communities of Paterson, Clifton and Morristown.

According to town Administrator Sanford Kaplan, a typical two-bedroom home in the borough averages $140,000. Kaplan said he bought a two-bedroom home two years ago in an earlier Hovnanian development there, Society Hill, for $82,000. He said it's now worth about $145,000.

The housing market is tight in most of northern New Jersey, home to New York commuters and employees at manufacturing and commercial centers in New Jersey.

Of the 260 units to be finished at Society Hill II, 50 have been reserved for state-mandated middle- and low-income housing and 10 are being set aside for buyers already promised homes.

Kevork Hovnanian, Ara Hovnanian's 62-year-old father, is an Iraqi immigrant of Armenian descent who founded the company in 1959.

For 1985, Builder magazine ranked Hovnanian Enterprises as 32nd in its listing of the nation's 100 top builders.

''Hovnanian is a groundbreaker'' in the area of moderately priced homes, said Carol Anderson, the magazine's news editor. ''They seem to be a pioneer in these mass marketing techniques,'' she said.

Ms. Anderson, speaking by telephone from her Washington, D.C., office, said the company can afford to build less expensive homes by building so many - 3,400 last year, mostly condominiums.

''They produce a lot of affordable housing. And they happen to be in a very good market,'' she said.