In the UserForm module the output from the UserForm is a generic date of the form "Jul 6, 2015". You can use the Format Statement (red) in the code below to format the output as you require. 'dddd' will give you 'Tuesday', and 'ddd' will give you 'Tue'.
Private Sub CommandButton2_Click()
  'This gets a date using a Calendar Form Date Picker
  
  Dim sDateString As String
  Dim sSeedDateString As String
  
  'Get the Seed Date
  sSeedDateString = Sheets("Main").Range("L12").Value
  
  sDateString = LjmGetDateUsingCalendarForm(sSeedDateString)
  
  UserForm1.Label1.Caption = "The date selected by 'LjmGetDateUsingCalendarForm' was: " & Format(sDateString, "ddd mmmm d, yyyy")
End Sub
To adapt the other code to UserForms:
a. I usually use the 'Enter' Event in a UserForm to implement the other 'Picker' code. For example, using 'TextBox1':
Private Sub TextBox1_Enter()
  Dim s As String
  Dim sStartStringPath As String
  Dim sUserPrompt As String
  
  sStartStringPath = ThisWorkbook.Path & "\"
  sUserPrompt = "Select a File and 'Click' on 'OK'"
    
  s = LjmGetFileUsingFilePicker(sStartStringPath, sUserPrompt)
  
  TextBox1.Value = s

End Sub