Yes, it is possible and Spices.Net Obfuscator already supports it.
You can use Spices.Projects ObfuscationEvents to use PostSharp before and after obfuscation (each assembly or whole obfuscation project) to allow PostSharp to include the extra "name table" resource in the assembly (before obfuscation) and process the assembly (after obfuscation). Spices.Net Obfuscator provides wide range of obfuscation events, so that's easy to integrate PostSharp in any of build or obfuscation processes (MSBuild, Visual Studio, NAnt, Spices.Net GUI or command line).