You would use ADO to do the call. Some quick code look like:
Dim cn As ADO.DB.Connection
Dim cmd As ADODB.Command
Dim pmt As ADO.Parameter
''Create connecction to SQL Server database
SET cn=New ADODB.Connection
cn.Open myConnectionString
''Create Command Object
Set cmd=New ADODB.Command
cmd.CommandType=adCmdStoredProc
cmd.CommandText="myStoredProcedureName"
Set cmd.ActiveConnection=cn
''Set up parameters if needed
Set pmt=cmd.CreateParameter(......)
cmd.Parameters.Append pmt
....
'Finally execute the command
''Then you can retrieve output parameter value, or store return RecordSet on
an AADODB.recordSet
cmd.Execute
or
Dim rs As ADODB.recordSet
Set rs=cmd.Execute
cn.Close
.....