TriMeshes should only really be used for static scenery, they're much slower than primitives (boxes, spheres and cylinders).
Any meshes can be used to represent any type of ODE object, just change the ode\mesh to whatever you want... ode\mesh=LoadMesh("mesh.3ds")
To create a barrel with a custom mesh, you should create a cylinder ODE geom (ode\geom) and use the 'barrel.3ds' for the visible mesh (ode\mesh).
Any meshes can be used to represent any type of ODE object, just change the ode\mesh to whatever you want... ode\mesh=LoadMesh("mesh.3ds")
To create a barrel with a custom mesh, you should create a cylinder ODE geom (ode\geom) and use the 'barrel.3ds' for the visible mesh (ode\mesh).