First thing to do is to choose one of the T2 Linux versions and download it from http://www.t2sde.org/ (see also the section called “Stable branches versus trunk”). A tarball of the distribution scripts is only a few MB in size and downloads quickly.
T2's stable versions go hand-in-hand with stable Linux kernel versions. Nevertheless most T2 users use the development versions of T2 Linux anyway . One addicting feature of T2 is that you get the latest version of every package, including the kernel. The development versions of T2 have proved to be pretty robust. Nevertheless a development version can potentially be broken.
Untar the file and it unpacks documentation, build scripts and the directories with package definitions.
The size of T2 Linux is so small because it is only contains the build scripts and meta information for downloading the kernel and packages from the Internet. The rest of the distribution gets downloaded in the next phase.