If you want to deploy your application to be able to use both 32-bit and 64-bit .NET, you need to build liblmxnet.dll with both the 32 bit and 64 bit .NET compiler (these files should be shipped with your application).
Note: Both liblmxnet.dll files should use the same key pair.
For example, the build may look as follows:
C:\Program Files\X-Formation\LM-X SDK v4.8.4 win64_x64>(configure your environment for 64-bit compilation)
C:\Program Files\X-Formation\LM-X SDK v4.8.4 win64_x64>nmake
C:\Program Files\X-Formation\LM-X SDK v4.8.4 win64_x64\win64_x64\x-formation_pair.snk
Copy to
C:\Program Files (x86\X-Formation\LM-X SDK v4.8.4 win32_x86\win32_x86\x-formation_pair.snk
C:\Program Files (x86\X-Formation\LM-X SDK v4.8.4 win32_x86>(configure your environment for 32-bit compilation)
C:\Program Files (x86\X-Formation\LM-X SDK v4.8.4 win32_x86>nmake