Your best bet is to set up Web Access on your Laserfiche Server and use the web access client from the Ubuntu machine. Anything else would be more work and effort than its worth. This is how I was able to get a customer able to use Laserfiche with OS/X.

When you factor in the amount of hours and frustration you'd spend trying to get WINE or even a VM to work with the client, you'd have been better off just setting up a separate physical windows machine just to run the Laserfiche Client.

WINE is a very incomplete implementation of the Windows application programming interface (API). It is incomplete in the sense that if the application tries to use a functionality that is implemented by Microsoft Windows but is not implemented in WINE, the application will generally crash in an unrecoverable way. Data will likely be corrupted.

On the other hand, I am confident that Laserfiche applications can be installed on a Windows guest OS inside a VMware instance under a Linux host OS.

In fact, new Laserfiche customers are encouraged to practice their Laserfiche administrative skills on an installation of Laserfiche on VM. VMware's virtual machine snapshot capability gives you the peace of mind when you need to experiment with some administrative tasks.