Clipboard Mac guest to Mac host

[DFspx]

Due to missing legacy support, I need to run an Mac OS 10.6 with Rosetta inside a virtualbox on a Mac OS 10.9.
I got that mostly working, but the clipboard does not allow copying text data and/or files between the systems.

I searched a lot for ways to make it work, but the guest additions for mac guest doesn't seem to exist anymore and all other hints I found are assuming a different guest/host configuration.
Is there any way to get the clipboard operational between guest and host?

Hardware: Mac Pro (manufactured End 2013)
Host: Mac OS 10.9
VM: 4.3.12
Guest: Mac OS 10.6

[mpack]

There are no Guest Additions for an OS X guest, hence no shared clipboard (and no GA shared folders).

You need to think of it as two separate PCs: the VM is not an application running on your host. Do whatever you would normally do to transfer data between two physically separate PCs. A true network share is probably the most convenient solution.

[DFspx]

I'm already using network folders instead of shared folders, but I haven't found a way with the clipboard.

Is there no alternative to the GA's?
A third-party software or some tricks to transfer clipboard data?

(edit: the problem is that the programs on 10.9 can't read the (thousands) old Appleworks files, and transferring all those files through PDF is not only a lot of work, but also removes part of the functionality)

[mpack]

You want a tool that shares the clipboard across a network connection. It helps that you already have a network connection working for the purpose of sharing folders. It probably doesn't help that you're networking Macs: you probably need to ask about that in a Mac forum, since it isn't a VirtualBox question.

[ChipMcK]

Back-To-My-Mac includes 'shared clipboard' support [screen sharing]

and file transfer [file sharing]

Edited to include 'file transfer'