add detailed build instructions to README

README.md

-# slic
+# SLIC
+
 Simulation for the Linear Collider (SLIC) Geant4 simulation application
+
+## Installation
+
+For now the installation is done manually by first building SLIC's dependencies and then the main package.  Step-by-step instructions are given below.
+
+### Tools
+
+    * gcc 4.8 or greater (prob 4.9 or greater is preferable)
+        * You cannot use the default gcc on RHE6 or similarly old distros so you would need to install one yourself or use a dev toolset.
+    * CMake ~3.0 or greater (tested with 3.6)
+
+### Initial Setup
+
+There will be a `build` dir where all the packages are built and configured and an `install` dir where they are installed out of source.  
+
+This structure can be setup as follows:
+
+```
+cd /scratch
+mkdir slic; cd slic
+mkdir install; cd install
+export install_dir=$PWD
+cd ..
+mkdir build; cd build
+```
+
+### Geant4
+
+Download the 10.3.p01 tarball from the Geant4 website and untar it or you may clone a tag from the Geant4 github.
+
+```
+cd geant4.10.03.p01; mkdir build; cd build
+cmake -DGEANT4_INSTALL_DATA=ON -DCMAKE_INSTALL_PREFIX=$install_dir/geant4 ..
+make -j4
+make install
+```
+
+### LCIO
+
+```
+git clone https://github.com/iLCSoft/LCIO.git lcio
+cd lcio; mkdir build
+cmake -DINSTALL_DOC=OFF -DCMAKE_INSTALL_PREFIX=$install_dir/lcio ..
+make -j4
+make install
+```
+
+## HepPDT
+
+```
+wget http://lcgapp.cern.ch/project/simu/HepPDT/download/HepPDT-3.04.01.tar.gz
+tar -zxvf HepPDT-3.04.01.tar.gz
+cd HepPDT-3.04.01
+./configure --prefix=/u/ey/jeremym/hps-dev/slic/install/heppdt .. --disable-static
+make install
+```
+
+## Xerces
+
+```
+./configure --prefix=/u/ey/jeremym/hps-dev/slic/install/xerces
+make
+make install
+```
+
+### GDML
+
+```
+git clone https://github.com/slaclab/gdml
+cd gdml; mkdir build; cd build
+cmake -DGeant4_DIR=/u/ey/jeremym/hps-dev/slic/install/geant4/lib64/Geant4-10.3.1/ -DXERCES_DIR=/u/ey/jeremym/hps-dev/slic/install/xerces/ -DCMAKE_INSTALL_PREFIX=/u/ey/jeremym/hps-dev/slic/install/gdml ..
+make -j4 install
+```
+
+### LCDD
+
+```
+git clone https://github.com/slaclab/lcdd
+cd lcdd; mkdir build; cd build
+cmake -DINSTALL_DOC=OFF -DGeant4_DIR=$install_dir/geant4/lib64/Geant4-10.3.1/ -DGDML_DIR=$install_dir/gdml -DXERCES_DIR=$install_dir/xerces -DCMAKE_INSTALL_PREFIX=$install_dir/gdml ..
+make -j4 install
+```
+
+### SLIC
+
+```
+cmake -DINSTALL_DOC=OFF -DCMAKE_INSTALL_PREFIX=$install_dir/slic -DXERCES_DIR=$install_dir/xerces -DLCIO_DIR=$install_dir/lcio/ -DGeant4_DIR=$install_dir/geant4/lib64/Geant4-10.3.1/ -DGDML_DIR=$install_dir/gdml/ -DHEPPDT_DIR=$install_dir/heppdt -DLCDD_DIR=$install_dir/lcdd ..
+```
+
+## Running SLIC
+
+```
+source /scratch/slic/install/slic/bin/slic-env.sh
+slic [options]
+```