Creating a Custom Toolbar/Buttons

Code to call a geoprocessing tool from VBA button:

Private Sub UIButtonControl1_Click()
 Dim pApp As IApplication
 Set pApp = Application

 Dim pUID As New UID
 pUID = "esriGeoprocessingUI.ArcToolboxExtension"

 Dim pATBExt As IArcToolboxExtension
 Set pATBExt = Application.FindExtensionByCLSID(pUID)

 Dim pAtb As IArcToolbox
 Set pAtb = pATBExt.ArcToolbox

 Dim pTool As IGPTool
 Set pTool = pAtb.GetToolbyNameString("buffer_analysis")

 Dim pParams As IArray
 Set pParams = pTool.ParameterInfo

 Dim pParameter As IGPParameter
 Dim pParamEdit As IGPParameterEdit
 Dim pDataType As IGPDataType
 Dim sValue As String

 'First Parameter
 Set pParameter = pParams.Element(0)
 Set pParamEdit = pParameter
 Set pDataType = pParameter.DataType
 sValue = "D:\workspace\Newfoundland.mdb\roads"
 Set pParamEdit.Value = pDataType.CreateValue(sValue)

 'Second Parameter
 Set pParameter = pParams.Element(1)
 Set pParamEdit = pParameter
 Set pDataType = pParameter.DataType
 sValue = "D:\workspace\Newfoundland.mdb\roads_buf"
 Set pParamEdit.Value = pDataType.CreateValue(sValue)

 'Third Parameter
 Set pParameter = pParams.Element(2)
 Set pParamEdit = pParameter
 Set pDataType = pParameter.DataType
 sValue = "500 Meters"
 Set pParamEdit.Value = pDataType.CreateValue(sValue)

 Dim pCommand As IGPToolCommandHelper
 Set pCommand = New GPToolCommandHelper
 pCommand.SetTool pTool
 pCommand.Invoke pParams
End Sub
Also need to ensure the ESRI GeoprocessingUI Libraries is referenced.