I'd use the PropertySelect or write my own custom property for this and just inherit from PropertyString and PropertySelectControlBase.

Eg:

[Serializable]
[PageDefinitionTypePlugIn]
public class PropertyWeekNumberDropDown : PropertyString
{
	public override IPropertyControl CreatePropertyControl()
	{
		return new PropertyWeekNumberDropDownControl();
	}
}


public class PropertyWeekNumberDropDownControl : PropertySelectControlBase
{
	protected override void SetupEditControls()
	{
		this.SetupDropDownList();
	}

	private void SetupDropDownList()
	{
		this.EditControl.DataSource = GetWeekNumbers;

		if (this.WeekNumberDropDown.Value != null)
		{
			this.EditControl.SelectedValue = this.WeekNumberDropDown.Value as string;
		}

		this.EditControl.DataBind();
	}

	private static string[] GetWeekNumbers
	{
		get
		{
			var weekNumbers = new string[54];
			weekNumbers[0] = "Velg uke";
			for (int i = 1; i <= 53; i++)
			{
				weekNumbers[i] = i.ToString();
			}

			return weekNumbers;
		}
	}

	public PropertyWeekNumberDropDown WeekNumberDropDown
	{
		get
		{
			return PropertyData as PropertyWeekNumberDropDown;
		}
	}
}

Then in your dynamic content user control:

public PropertyWeekNumberDropDown WeekNumber { get; set; }

Thanks Frederik.  Ill give it a shot and see what happens.  Appreciate your quick response.