Ho trovato la soluzione. Dato che potrebbe essere utile ad altri, la incollo qui di seguito:

On the newsgroup somebody asked how to have multiple lines of text on a .NETCF Button control. The native control supports this but the appropriate style is not set by default. The following code snippet shows how to enable this:-

codice:
private const int BS_MULTILINE = 0x00002000;
private const int GWL_STYLE = -16;

[System.Runtime.InteropServices.DllImport("coredll")]
private static extern int GetWindowLong(IntPtr hWnd, int nIndex);

[System.Runtime.InteropServices.DllImport("coredll")]
private static extern int SetWindowLong(IntPtr hWnd, int nIndex, int dwNewLong);

public static void MakeButtonMultiline(Button b)
{
    IntPtr hwnd = b.Handle;
    int currentStyle = GetWindowLong(hwnd, GWL_STYLE);
    int newStyle = SetWindowLong(hwnd, GWL_STYLE, currentStyle | BS_MULTILINE);
}
The usage is simple, just pass the specific Button control to MakeButtonMultiline:-

codice:
MakeButtonMultiline(button1);
L'ho provato, e funziona alla perfezione .

Ciao