Problem with exporting Textures with Dex Script

I've just started to model with Gmax, and after creating my first model I wanted to export it.

The exporting worked fine, and I copied and pasted each part of the model respectively into an MDL file (because of the MaxScript bug of only being able to select a small part of the model at once) and I noticed that there was only one field for Textures, while I had made in the model three skins for the three diferent meshes. How would I change the Export or edit the MDL file that it will include all three texture?

Oh, and by the way, it's a bed model. Please give suggestions or comment on the model.

Click the thumbnail to see it full size^^.

The skin will bve changed later, I just used that simple skin to attempt UVW Unwrapping.

Thank you for your time.