I ended up creating an extender class. Here is an example.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace LANDesk.Install.Common.Extenders
{
    public static class DateTimeExtender
    {
        #region Functions
        /// <summary>
        /// Methods to convert DateTime to Unix time stamp
        /// </summary>
        /// <param name="_UnixTimeStamp">Unix time stamp to convert</param>
        /// <returns>Return Unix time stamp as long type</returns>
        public static long ToUnixTimestamp(this DateTime thisDateTime)
        {
            TimeSpan _UnixTimeSpan = (thisDateTime - new DateTime(1970, 1, 1, 0, 0, 0));
            return (long)_UnixTimeSpan.TotalSeconds;
        }

        #endregion
    }
}

Here is some code you can use for learning, to know what functions do what with DateTime. You should be able to learn everything you need to know by evaluating it.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace UTC
{
    class Program
    {
        static void Main(string[] args)
        {
            DateTime dt = DateTime.Now;

            Console.WriteLine("Outputting the type of DateTime object used:");

            Console.WriteLine(dt.Kind);

            Console.WriteLine("\nOutputting the current time as is:");

            Console.WriteLine(dt);

            Console.WriteLine("\nOutputting the current time using the ToUniversalTime() function:");

            Console.WriteLine(dt.ToUniversalTime());

            Console.WriteLine("\nOutputting the current time using the ToFileTime() function:");

            Console.WriteLine(dt.ToFileTime());

            Console.WriteLine("\nOutputting the current time using the ToFileTimeUtc() function:");

            Console.WriteLine(dt.ToFileTimeUtc());

            Console.WriteLine("\nOutputting the current time using the Ticks property:");

            Console.WriteLine(dt.ToFileTimeUtc());

            Console.WriteLine("\nCreating a DateTime and setting it as follows:\nDateTime udt1 = DateTime.Parse(\"1/1/1970\");");

            DateTime udt1 = DateTime.Parse("1/1/1970");

            Console.WriteLine(udt1);

            Console.WriteLine("\nCreating a DateTime and setting it as follows:\nnew DateTime(1970, 1, 1, 0, 0, 0, 0);");

            DateTime udt2 = new DateTime(1970, 1, 1, 0, 0, 0, 0);

            Console.WriteLine(udt1);

            Console.WriteLine("\nOutputting the time stamp of this Unix Time Stamp value: 1254322574 (seconds)\nTo do this i use these lines:\n DateTime udt1 = new DateTime(1970, 1, 1, 0, 0, 0, 0);\n udt.AddSeconds(1254322574448);");

            Console.WriteLine(udt1.AddSeconds(1254322574));

            Console.WriteLine("\nOutputting the time stamp of this Unix Time Stamp value: 1254322574789 (milliseconds)\nTo do this i use these lines:\n DateTime udt1 = new DateTime(1970, 1, 1, 0, 0, 0, 0);\n udt.AddMilliseconds(1254322574448);");

            Console.WriteLine(udt1.AddMilliseconds(1254322574789));

        }
    }
}

Ok, so here is the output:

Outputting the type of DateTime object used:
Local

Outputting the current time as is:
9/30/2009 3:49:18 PM

Outputting the current time using the ToUniversalTime() function:
9/30/2009 9:49:18 PM

Outputting the current time using the ToFileTime() function:
128988209584600486

Outputting the current time using the ToFileTimeUtc() function:
128988209584600486

Outputting the current time using the Ticks property:
128988209584600486

Creating a DateTime and setting it as follows:
DateTime udt1 = DateTime.Parse(“1/1/1970”);
1/1/1970 12:00:00 AM

Creating a DateTime and setting it as follows:
new DateTime(1970, 1, 1, 0, 0, 0, 0);
1/1/1970 12:00:00 AM

Outputting the time stamp of this Unix Time Stamp value: 1254322574 (seconds)
To do this i use these lines:
DateTime udt1 = new DateTime(1970, 1, 1, 0, 0, 0, 0);
udt.AddSeconds(1254322574448);
9/30/2009 2:56:14 PM

Outputting the time stamp of this Unix Time Stamp value: 1254322574789 (milliseconds)
To do this i use these lines:
DateTime udt1 = new DateTime(1970, 1, 1, 0, 0, 0, 0);
udt.AddMilliseconds(1254322574448);
9/30/2009 2:56:14 PM
Press any key to continue . . .