First, install wine in order to run win32 applications:
# sudo pacman -S wine wine_gecko lib32-mpg123 lib32-libxml2 lib32-openal lib32-libpng
You will also need this package from the [multilib] repository:
# sudo pacman -S lib32-libldap
Once the packages are installed, as a egular user run winecfg (win32)
# WINEARCH=win32 winecfg
# wine SugarSyncSetup.exe
Follow the instructions while keeping the default options. When done, uncheck the box "Run SugarSync" and click finish.