I had the same problem yesterday whe the Multibeast 5.0.2 installation would always fail, no matter which boxes were ticked. I found as solution that helped me (fresh install of ML):
I ran the installation of ML, then first started Multibeast for Lion (4.6.1) and only checked "UserDSDT Install". Installation was succesfull.
Afterwards I ran Multibeast 5.0.2, checked "UserDSDT or DSDT-Free Installation" and now it worked reproducable.
It wouldn't work a single time (tried it about 20 times, got VERY frustrated) when I would run Multibeast 5.0.2 directly.
Now my Hackintosh is finally up and running. Sound is working, got my WiFi D-Link dongle working, time machine is up an running. I even managed to send some files via Airdrop to my MacBook Air, though it only works in direction Hackintosh to Mac, not the other way round.
For what it matters, here's my system:
Gigabyte Z77 UP5 TH
Intel i7 3770k
G.Skill Ares PC12800 Ram
Samsung 830 SSD 256 GB (plus several drives from my old PC built)
HD 4870 (will be replaced by GTX 670 after next paycheck arrives