This should help get the runtime built.
FOR D1:
=======
1) Do a checkout of tango trunk into the ldc root dir (along dmd, gen, runtime etc).

    *   $ ls
    *   dmd dmd2 gen ir ...
    *   $ svn co http://svn.dsource.org/projects/tango/trunk tango

2) Compile the runtime

    *   sh build.sh

FOR D2:
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1) Check http://bitbucket.org/prokhin_alexy/ldc2/wiki/Home for up to date instructions

2) At the time of writing, this works:

    *   $ git clone https://github.com/AlexeyProkhin/druntime
    *   $ git clone https://github.com/AlexeyProkhin/phobos

3) Using cmake, set the D version to 2, then set the correct paths for druntime and phobos

4) Compile ldc2, druntime, and phobos

    *   $ make phobos2

=======
Enjoy!