cygwin中如何安装低版本的gcc

ghostkui

最近安装tinyos系统，里面的交叉编译用的是gcc4.1，而cygwin的gcc是4.8，所以安装套件时出现下面问题：

软件包 avr-libc-1.4.7-1.i386 是针对 different 操作系统的
        file /usr from install of avr-libc-1.4.7-1.i386 conflicts with file from package avr-binutils-2.17tinyos-3.i386
        file /usr/avr from install of avr-libc-1.4.7-1.i386 conflicts with file from package avr-binutils-2.17tinyos-3.i386
        file /usr/avr/lib from install of avr-libc-1.4.7-1.i386 conflicts with file from package avr-binutils-2.17tinyos-3.i386
        file /usr/bin from install of avr-libc-1.4.7-1.i386 conflicts with file from package avr-binutils-2.17tinyos-3.i386
        file /usr from install of avr-libc-1.4.7-1.i386 conflicts with file from package avr-gcc-4.1.2-1.i386
        file /usr/avr from install of avr-libc-1.4.7-1.i386 conflicts with file from package avr-gcc-4.1.2-1.i386
        file /usr/avr/lib from install of avr-libc-1.4.7-1.i386 conflicts with file from package avr-gcc-4.1.2-1.i386
        file /usr/bin from install of avr-libc-1.4.7-1.i386 conflicts with file from package avr-gcc-4.1.2-1.i386
        file /usr/share from install of avr-libc-1.4.7-1.i386 conflicts with file from package avr-gcc-4.1.2-1.i386

请问我如何安装低版本的gcc，不卸载已有版本的gcc可以不？