dotnetfx.exe /q:a /c:"install /l /q"
NDP1.1sp1-KB867460-X86.exe /qb

Source:msdn - .NET Framework Redistributable Package 1.1 Technical Reference

NetFx20SP1_x86.exe /q

dotnetfx35sp1.exe /passive /norestart

dotnetfx35sp1.exe also installs .NET 2.0 SP2 and .NET 3.0 SP2.

First install the Windows Imaging Component:

wic_x86_enu.exe /passive /norestart

Then install .NET 4.0:

dotNetFx40_Full_x86_x64.exe /passive /norestart