At first, if you want to follow installer best practices, I wouldn't recommend installing prerequisites using custom actions.
Speaking about your question, here is my implementation of custom bootstrapper in C#:
using System;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace SetupBootstrapper
{
class Program
{
[STAThread]
static void Main(string[] args)
{
var currentDir = AppDomain.CurrentDomain.BaseDirectory;
var parameters = string.Empty;
if (args.Length > 0)
{
var sb = new StringBuilder();
foreach (var arg in args)
{
if (arg != "/i" && arg != "/x" && arg != "/u")
{
sb.Append(" ");
sb.Append(arg);
}
}
parameters = sb.ToString();
}
bool isUninstall = args.Contains("/x") || args.Contains("/u");
string msiPath = Path.Combine(currentDir, "MyMsiName.msi");
if(!File.Exists(msiPath))
{
MessageBox.Show(string.Format("File '{0}' doesn't exist", msiPath), "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
return;
}
string installerParameters = (isUninstall ? "/x" : "/i ") + "\"" + msiPath + "\"" + parameters;
var installerProcess = new Process { StartInfo = new ProcessStartInfo("msiexec", installerParameters) { Verb = "runas" } };
installerProcess.Start();
installerProcess.WaitForExit();
}
}
}
To make it ask for elevated permissions I add application manifest file into project with desired access level.
The drawback of implementing bootstrapper in .NET is of course that you can't adequately process situation when .NET is a prerequisite itself and may be absent on target machine.