how could i add a model onto earth with a lng and lat location

[cll131421]

First of all ,I apologize for my poor english;
Now i have a problem with add model to celestia;
As i know,celestia's model system is just like a close system;
Celestia read data from types of files and initialize the model system quietly;
Is there a way to add my model to the system?
And what should i do?
I want to add a model onto earth and location it with lng an lat info,
I want to control where the model is real time ,so i can't make it as an add on;
Any one help ME?
3Q very much;