プリンタ名とポート名を取得します。
EnumPrinters プリンタの詳細な情報を取得 
CopyMemory ある位置から別の位置にメモリブロックを移動 
PrinterProperties プリンタ設定ダイアログ表示 
SetDefaultPrinter 通常使うプリンタの設定 
OpenPrinter プリンタオブジェクトをオープン 
ClosePrinter プリンタオブジェクトを閉じる 

'================================================================
'= プリンタ名とポート名を取得
'=    (EnumPrinters.bas)
'================================================================
#include "Windows.bi"

' 詳細なプリンタ情報を定義する構造体
Type PRINTER_INFO_5
    pPrinterName             As Long
    pPortName                As Long
    Attributes               As Long
    DeviceNotSelectedTimeout As Long
    TransmissionRetryTimeout As Long
End Type

#define PRINTER_ENUM_NAME &H8           'Nameで指定されたプリンタを列挙
#define MAX_DEVICENAME 64               '

' プリンタの詳細な情報を取得
Declare Function Api_EnumPrinters& Lib "winspool.drv" Alias "EnumPrintersA" (ByVal Flags&, ByVal Name$, ByVal Level&, pPrinterEnum As Any, ByVal cdBuf&, pcbNeededed&, pcReturned&)

' ある位置から別の位置にメモリブロックを移動
Declare Sub CopyMemory Lib "Kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length&)

' プリンタ設定ダイアログ表示
Declare Function Api_PrinterProperties& Lib "winspool.drv" Alias "PrinterProperties" (ByVal hWnd&, ByVal hPrinter&)

' 通常使うプリンタの設定
Declare Function Api_SetDefaultPrinter& Lib "winspool.drv" Alias "SetDefaultPrinterA" (ByVal pszPrinter$)

' プリンタオブジェクトをオープン
Declare Function Api_OpenPrinter& Lib "winspool.drv" Alias "OpenPrinterA" (ByVal pPrinterName$, phPrinter&, pDefault As Any)

' プリンタオブジェクトを閉じる
Declare Function Api_ClosePrinter& Lib "winspool.drv" Alias "ClosePrinter" (ByVal hPrinter&)

Var Shared List1 As Object
Var Shared Button1 As Object

List1.Attach GetDlgItem("List1") : List1.SetFontSize 14
Button1.Attach GetDlgItem("Button1") : Button1.SetFontSize 14

'================================================================
'=
'================================================================
Declare Sub Button1_on edecl ()
Sub Button1_on()
    Var PrinterServer As String
    Var PrinterName As String
    Var PortName As String
    Var Needed As Long
    Var Returned As Long
    Var Level As Long
    Var i As Long
    Var Ret As Long

    PrinterServer = ""
    Level = 5

    List1.ResetContent

    Ret = Api_EnumPrinters(PRINTER_ENUM_NAME, PrinterServer, Level, Chr$(0), 0, Needed, Returned)
    If Needed = 0 Then End

    Var Buffer(Needed - 1) As Byte
    Ret = Api_EnumPrinters(PRINTER_ENUM_NAME, PrinterServer, Level, Buffer(0), Needed, Needed, Returned)

    Var pi5(Returned - 1) As PRINTER_INFO_5

    For i = 0 To Returned - 1
        CopyMemory pi5(i), Buffer(i * Len(pi5(i))), Len(pi5(i))

        'プリンタ名取得
        PrinterName = String$(MAX_DEVICENAME, Chr$(0))
        CopyMemory PrinterName, ByVal pi5(i).pPrinterName, Len(PrinterName)
        PrinterName = Left$(PrinterName, InStr(PrinterName, Chr$(0)) - 1)
        List1.AddString PrinterName

        'ポート名取得
        PortName = String$(MAX_DEVICENAME, Chr$(0))
        CopyMemory PortName, ByVal pi5(i).pPortName, Len(PortName)
        PortName = Left$(PortName, InStr(PortName, Chr$(0)) - 1)

        List1.AddString "  " & PortName
    Next
End Sub

'================================================================
'=
'================================================================
Declare Sub List1_Change edecl ()
Sub List1_Change()
    Var hPrinter As Long
    Var Ret As Long

    PrinterName$ = List1.GetText(List1.GetCursel)

    Ret = Api_SetDefaultPrinter(PrinterName$)
    Ret = Api_OpenPrinter(PrinterName$, hPrinter, ByVal 0)
    Ret = Api_PrinterProperties(GethWnd, hPrinter)
    Ret = Api_ClosePrinter(hPrinter)
End Sub

'================================================================
'=
'================================================================
While 1
    WaitEvent
Wend
Stop
End