In a 150g, you might be able to pull it off, but prepare to have heavy losses - Serra's arent shoaling fish, not even Spilo's, Macs or Geryi. They tolerate each other's presence in a tank large enough, but don't shoal.
Understanding that, and knowing about the difference between shoaling in the Pygo-sense on the one hand, and the cohabitation of Serra's on the other hand is vital to even have a remote chance of succes - they are two entirely different things!
If you want to give it a try, I'd get 6-8 juvi's (2-3" max.), so they'll sort things out amongst themselves, and you end up with the toughest and fittest specimen. Keep the temperature somewhat on the low side - 76-78 degrees F - and add lots and lots of decor, so they fish can get away from the others if they feel the need to.
Other than that, keep them well-fed, perhaps add a constant supply of dither fish such as tetra's, small cichlids or life bearers (stay away from Cyprinids, such as goldfish, koi, barbs, danio's and other carp-like fish), and hope for the best.
A member named Winkyee has kept a shoal of Macs for a good amount of time, so maybe he can give you some more useful tips. And there were/are a few more, but I forgot their names...
Good luck, but before you start, reconsider it - the worst-case scenario is a frustrating, fruitless effort and a lot of time and money wasted. If you start a 'project' like this without thorough planning and gathering info, you'll go downhill from the very first second: that just a handful of people managed to have long-term succes is not without reason!