Is it possible from a PC using a Citrix ICA Client to connect to Citrix XenApp, then from the XenApp have a RDP remote desktop connection a Server, then map a disk on the Server, such that the mapped disk is available from the PC?
I would suggest that you install Hamachi or something similar on both your local PC and then Server. This will allow you to create a private VPN directly between these two computers. You can then browse to the server over network neighborhood and mount your network share that way. For a simple comparison of these products, see: http://cubicgarden.com/tag/hamachi/