This is how I do it in
VB.net 2005. I know you asked for VB6, maybe it will help?
Code:
Private Sub RichTextBox1_SelectionChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles RichTextBox1.SelectionChanged
'Get the line number and colom number and show it
Dim intFirstChar As Integer = Me.RichTextBox1.GetCharIndexFromPosition(New Point(0, 0))
Dim intFirstLine As Integer = Me.RichTextBox1.GetLineFromCharIndex(intFirstChar)
Dim intCharCount As Integer = (Me.RichTextBox1.SelectionStart + Me.RichTextBox1.SelectionLength) - intFirstChar
Dim strFromStart As String = Me.RichTextBox1.Text.Substring(intFirstChar, intCharCount)
Dim intLine As Integer = strFromStart.Split(vbLf).Length
' This is the Row Number
Me.lblLine_Counter.Text = (intFirstLine + intLine)
' This is the Column Number
Me.Label1.Text = "Column: " & (intCharCount - strFromStart.LastIndexOf(vbLf))
End Sub