怎么安装多版本的GCC编译器，又不冲突？如何设置？

情况是这样的，我要安装一个软件（abinit 6.0.4）,这个软件需要用GNU4.2以上版本编译才行。而我原来系统中的编译器是GNU4.1的。后来我问了系统管理员，他叫我安装新版本的编译器到自己目录上，后来我直接在网上下载了可以直接用的GNU4.4。
下面我的问题就是：
1，怎么设置，才能使得我能用GNU4.4去编译我要安装的软件。
2，在我要安装的软件的说明中有说到configure的几个选项：不知道有没有人知道该如何设置？选项如下：

# ---------------------------------------------------------------------------- #
# Fortran support #
# ---------------------------------------------------------------------------- #

# Fortran compiler
#
#FC="gfortran"

# Set debug flags for Fortran source files (overrides auto-detection)
#
#with_fc_dbgflags="-g"

# Set optimizations for Fortran source files (overrides auto-detection)
#
with_fc_optflags="-O2"

# Prepend debug link flags for Fortran binaries (default is unset)
#
#with_fc_ld_dbgflags=""

# Prepend optimization link flags for Fortran binaries (default is unset)
#
#with_fc_ld_optflags="-Bstatic"

# Append debug libraries to link Fortran binaries (default is unset)
#
#with_fc_ld_dbglibs=""

# Append optimization libraries to link Fortran binaries (default is unset)
#
#with_fc_ld_optlibs="-lsvml"

# Use C clock instead of Fortran clock for timings (default is no)
#
#enable_cclock="yes"

# Choose whether to read file lists from standard input or "ab.files"
# (default is yes = standard input)
#
#enable_stdin="no"

# Wrap Fortran compiler calls (default is auto-detected)
# Combine this option with enable_debug="yes" to keep preprocessed source
# files (they are removed by default, except if their build fails)
#
#enable_fc_wrapper="yes"