Yup. Take the shuttle from the airport to the Ronkonkama LIRR station.
There is shuttle service from MacArthur Airport to the nearby Ronkonkoma train station:
Colonial Transportation of Long Island offers convenient shuttle service between MacArthur Airport and the Ronkonkoma train station (LIRR). The shuttle van departs the train station daily at 5:30am, then departs the airport on the hour and half-hour from 6:00am until 10:30pm. Curbside pick up at the airport is directly in front of baggage claim. The shuttle will pick up and drop off at the North Platform of the Ronkonkoma train station. The one-way fare is $5.00 per person. Cash and credit cards are accepted. All rates are subject to change without notice.The Suffolk County Bus Transit also offers hourly service to and from MacArthur Airport to the train station with the S-57 Bus except Sundays and(No service, New Year's Day, Memorial Day, Independence Day, Labor Day, Thanksgiving Day or Christmas). The fare is $1.50.The Long Island Rail Road (LIRR) offers frequent service to Penn Station in Manhattan from the Ronkonkoma train station The train ride is approximately one hour and 25 minutes.The train fare currently $6.50 (non-rush hour times) into the city will take you to Penn station which is located in Manhattan at 33rd street and 7th Avenue.
http://www.islipairport.com/pages/transportation.shtml
From there you can walk, take a taxi, or take the 7th Ave bus to 23rd Street and hop on the M23 bus to 8th Ave and walk the rest. You will need a metrocard of $2.00 for the bus or exact change of $2. If you use change, ask for a transfer from the 7th Ave bus driver so you can get on the M23.