build legacy-support for an older OS than the host OS?

[René J . V . Bertin]

Hi,

Quick question to the legacysupport maintainers: is there a way to build the 
library as if on an older OS (10.7 or even 10.6) than the host OS (10.9.5 in my 
case)?

I do mean "by hand" of course, or using build variants in a private version of 
the port.

Thanks,
R.