You can use "list" type search and pass the array object as the value. DataAssist Search works with arrays directly. You probably still want to use "=" since you are looking for an exact match.
It won't exactly do an IN search, but it will achieve the same result with a complex WHERE statement joined by OR.... something like: WHERE (ID =23 OR ID=54 OR ID =34 OR ID = 76)
The same end result, so it should work for you.