DevForce Classic does not directly support spatial data, but you can work around the limitation.
Instead of defining the data column as a Geography type you can use varbinary(max), so that DevForce can read and write the column. Within your code you can then convert the byte array to a SqlGeography type when needed.
For example, when saving you can use STAsBinary to obtain the byte array to be saved in the database column. For example:
myEntity.MyGeoAsBinaryProp = mygeogVar.STAsBinary().Buffer
To create a SqlGeometry object from a queried entity you can use something like this:
Dim sqlBytes = New SqlBytes(myEntity.MyGeoAsBinaryProp)
Dim geog = SqlGeography.STGeomFromWKB(sqlBytes, mysrid)