Funny you ask, it's been a hot topic in my local circle too now that I've been getting rid of some.
When I was young we did knife hits. My wife would never let me stink up the kitchen like that now lol Instead of free flow we would have a 2 litre bottle with the bottom cut off as a funnel for the person inhaling, one time we cut the bottom of a 44oz beer bottle to use as a funnel. I think you get the most bang for your buck using knife hits but I'm not a kid anymore, I want it easy lol
Nowadays... I'm lazy. I found one way I like and that is to layer a bowl with herb, hash, herb. It will take me like 30 minutes to finish that bowl.... Phew

when I put hash in the middle like this I get a piece of hash and squeeze it as hard as I can to get it flat and thin.
But I think with that small bong I might try to use some kind of special hash smoking stem in it or something.
I remember using those little keychain novelty bowls for hash as a kid too.
Sometimes I put some in the Plenty, layering like a bowl.