If you do access your DataPower boxes via a VNC session as described over your company VPN from remote, your traffic from VPN server to your VNC server is not encrypted. These days end-to-end encryption should be done everywhere [remote-->VPN server-->VNC server and VNC server--(https)-->DataPower]. One option for this is to tunnel the VNC connection over SSH. There are many tutorials (it is really simple), this is one of them.
When connecting to Boeblingen lab by IBM VPN solution from home I can access all my DataPower boxes.
Even though I do have a 12Mbps DSL line at home, which allows for very fast downloads, working with WebGUI sometimes is much slower than in the office.
And that is even true when doing it at daytime when my children are at school [and do not use bandwidth for Internet games or youtube ;-)].
It seems that the added latencies for the many parts building up WebGUI make the difference.
I did find a simple solution for that -- just connect to a Linux workstation in the lab with a VNC viewer (see secreenshot below).
That workstation is connected by a 1Gbps line to the IBM network and does allow for really efficient access to my DataPower boxes
at Boeblingen lab (Germany), or to boxes in the US, at Prague or Taipei.
Connecting with VNC viewer has a second advantage -- I do have to use exactly one IBM application having Mainframe and Windows frontend only.
I just access the WinXP virtual image running on my workstation by "rdesktop" -- running there (see left bottom in screenshot) allows very quick data access
because of the 1Gbps line to the IBM network, and is far more efficient than running "rdesktop" from my IBM Laptop at home
just accessing the WinXP machine over DSL -- VNC is so much quicker than rdesktop.
Sceenshot of VNC session from home into the Boeblingen lab (click on screenshot to see it in full resolution):