I'm running into the same problem. [ regasm was successful over a network share in .net 3.5.]
And here's the reason why I would like to use regasm [and dont have the option modify regasm.exe.config]
Given that my COM interop assembly [strong named] has to be registered [ as part of a product] for use on other client's machines
while deploying, ideally I would like to continue using regasm [or some equivalent].
Also, technically if regasm is loading strong named assemblies , should this load be successful or any different ?
Finally what are the alternate solutions to regasm ?
1. I create a myproduct.reg file and am thinking of running it with the unc path since that does not involve regasm loading the exe over a network.
2. [assembly: SecurityRules(SecurityRuleSet.Level1)]
attribute to your DLL assembly properties, effectively switching off .NET4 security-transparent CAS.
Where do I do this, is this an entry in AssemblyInfo.cs ?
3. Using VS  to compile with COM interop.
Dont seem to see this option on project properties. Is this the COMVisible attribute in AssemblyInfo.cs that you are referring to ?
>> Another solution would be if you could simply check the option in Visual Studio for "compile with COM Interop".
>> This seems to work for me when building the DLL to the remote location
>> (VS does not use Regasm when registering an assembly).
What does VS use for registering COM interop assemblies [other than regasm?]
Any feedback will be really helpful.