I believe you can setup port forwarding rules in ipfwadm (once installed) to allow a VNC client to connect to your various workstations behind the e-smith gateway. A simpler way would probably be for you to use PPTP or IPSec to create a VPN between your e-smith server (samba file server) and your remote computer so that you can access your accounting files in true multi-user mode.
With the recent and ongoing popularity of VPNs, I can guess that we'll see some support for them in later releases of e-smith. I believe LRP (Linux Router Project) allows for IPSec, so as long as you're willing to make some modifications to your existing installation, you should be able to setup a VPN right now.
Sung H. Suh
ssuh@mobility.wox.org