There's no automatic methods to replay a ISS log file. However you could achieve that goal using your IIS log file as variable and then from NeoLoad Javascript you could modify the syntax to suit the NeoLoad syntax.

Then you can have an if...then...else logical action depending on if you would like to send a GET or POST request.

By setting a dynamic think time you can also define the speed of the execution.

Here is Javascript example that was used to replay an Apache log file. You could adjust it to suit your needs.

var myVar = context.variableManager.getValue("Access.Serveur");
if (myVar==null) {
        context.fail("Variable 'myVar' not found");
}
myVar=myVar.substring(0,myVar.indexOf(" -",0));
context.variableManager.setValue("Serveur",myVar) 

var URL = context.variableManager.getValue("Access.URL");
if (URL==null) {
        context.fail("Variable 'URL'' not found");
}

Method=URL.substr(0,1);
if (Method='G')
    {context.variableManager.setValue("method","0");
    }
else     {context.variableManager.setValue("method","1");
    }

var Request=URL.substring(URL.indexOf(" ",0)+1,URL.indexOf("HTTP",0)-1);
context.variableManager.setValue("Request",Request)