I would say that 90% of my custom menu bars call, and run my VBA code.

All you need to do is make the code (a function) public, and then simply
place the function name in the buttons on-action event code.

Further, likely often you will have specific code to a particular form, and
once again, you simply declare those functions (in that form) as public.

The syntax to call the code then is:

=YourFunctionName()

Often, (if not most of the time), you code you call will need to pick up
some information about he current screen etc. So, my code most of the time
starts out, and grabs the current screen name. I use:

Public Function AskInvoicePrint()

  Dim tblgroupid    As Long
  Dim frmActive     As Form

  Set frmActive = Screen.ActiveForm

  tblgroupid = frmActive.frmMainClientB.Form!ID

  If frmActive.InvoiceNumber = 0 Then
     frmActive.InvoiceNumber = nextinvoice
     frmActive.Refresh
  End If

  DoCmd.OpenForm "guiInvoicePrint", , , "id = " & tblgroupid

End Function

The above is code that the invoice print button runs. note how I right away
pick up the active form. After that, I can easily ref the forms object as if
the code was running much like the code would if put behind a button on the
form. In the above example, I also check if a invoice xnumber has been
generated before printing. And, the Refresh forces a disk write if in fact I
do change the invoice number. And, in addition the above clip also passes
the currently selected sub-form item that the invoice print form needs.

Also, if the code you write is for the particular form, then as mentioned,
you can simply place the code into the forms module code. There is no need
to pick up the active screen...and you can use me. as you
always used.

If you want to see some sample menu bars, and why I use them, you can read
the following:

http://www.members.shaw.ca/AlbertKallal/Articles/UseAbility/UserFriendly.htm