I think the best thing to do is learn enough of the other language so that you can rewrite by hand, there's some quite difficult differences in certain aspects that I'm not sure a converter would handle very well. For example, compare my translation from C# to VB of the following:
public class FileSystemEventSubscription : EventSubscription
{
private FileSystemWatcher fileSystemWatcher;
public FileSystemEventSubscription(IComparable queueName,
Guid workflowInstanceId, FileSystemWatcher fileSystemWatcher) : base(queueName, workflowInstanceId)
{
this.fileSystemWatcher = fileSystemWatcher;
}
becomes
Public Class FileSystemEventSubscription
Inherits EventSubscription
Private myFileSystemWatcher As FileSystemWatcher
Public Sub New(ByVal QueueName As IComparable, ByVal WorkflowInstanceID As Guid, ByVal Watcher As FileSystemWatcher)
MyBase.New(QueueName, WorkflowInstanceID)
Me.myFileSystemWatcher = Watcher
End Sub
The C# is from the Custom Activity Framework sample, and I'm afraid I've lost the link to it. But it contains some nasty looking inheritance (from a VB point of view).