Yep. If you're running it for a build, you're running unprivilaged - chrooted, jailed, or zoned if you want to be really safe - and if you're running it for install, than you trust the software in any case. And because makefiles are fairly transparent, you can check what the install is doing beforehand.
All you have to do now is make sure your hands are the right hands.
Like buddha said: right mind.