I am not entirely sure what you mean by a rock garden - blueberries prefer acidic soil conditions and plenty of sun, so if the rock garden has plenty of good soil which is acidic and in sun, they should grow.
You can grow from berries, but they don't come true from seed, so you won't know what you'll get if you do manage to grow some on. Its a bit of a performance, because the berries need cold stratification for some weeks, then they need macerating, the pulp removed, carefully, hopefully leaving behind some viable seeds. Those seeds need then to be planted in pots - full instructions here http://homeguides.sfgate.com/grow-blueberries-berry-75868.html
UPDATE - when you say 'lowbrush blueberry' I think you mean Vaccinium angustifolium and its variable relatives - that one prefers altitude, tends to grow on rocky ground, or ledges and the like, in fairly acid conditions. Whether trying to grow it in a rock garden to mimic its naturally preferred growing conditions will work isn't something I can predict, but here's a link about the plant generally, including where it is endemic, its somewhat variable offspring, and the conditions it generally chooses for itself https://gobotany.newenglandwild.org/species/vaccinium/angustifolium/