The short answer is:
Not directly. You would need to, as Tetsu0 said, save the model into a format that is used by another modeling program. See the end of this post for information on that.
The long answer:
The term "Model" is general and broad; there are many different forms of modeling and
very different ways of accomplishing the same task.
This program is a computer aided design (CAD) program which is a way of accomplishing the creation of a 3d model that is very different from the way most "gamers" are accustomed to, and would lack the tools necessary for a standard "game" model.
However, if someone really wanted to create something, in this case something exhibiting a necessity for some form of aerodynamic properties, then this package would help because it has an integrated finite element analysis (FEA) solver for fluid flow [referred to as computational fluid dynamics or CFD]. This would allow the user to check the design of their model for aerodynamic efficiency (Lift/Drag ratios, pressures on surfaces, etc.)
Although, it would be highly unnecessary and difficult to achieve the right scale relative to the game it shall be used in because of the nature of aircraft design. What I mean by that is that the program uses no units of measurement directly, it only uses relative scalars (Essentially ratios of different dimensions; eg: length/width/height/etc).
If after all this you would still wish to use this program you would need to have a few things.
You would have to have a program capable of importing the model the model data created by VSP as well as being able to export to the standard used by the game engine for which you are mapping for.From the user manual of VSP:
"Import
One can import information in different file formats, too. Currently, the program supports two file formats: Sterolith file (.stl) and NASCART file (bodyin.dat).
Export
Files may also be exported as well. Currently, the following formats are supported: Felisa file (.fel), Cross Section (XSec) file (.hrm), Sterolith file (.stl), Rhino3D file (.3dm), NASCART file (bodyin.dat), TecPlot file (.plt), STecPlot file (.plt), and Persistence of Vision Raytracer (.pov)."- For those of you TL:DR -This pretty much limits you to using the Stereolithography format, which luckily enough is capable of being imported into many other CAD programs as well as direct modeling programs such as Autodesk Maya, and 3DStudioMax.
So your process would be: Model in VSP, export to .stl, import .stl into modeling program, fix any mesh errors/visual problems, save it into a useable form for whatever engine you are going to use it for.
Though there is no guarantee that this will even directly compile into a model suitable for use in a game such as Half-Life. I would find it to be very interesting to see it done.