not sure if Deathwish's method will work...
but here is what I do.
1) make your model in whatever modeling program you have
2) export the thing as ".map"
3) copy all your texture files to the same folder your .map is saved in.
4) goto a command prompt, in the cmd prompt, goto the folder where your .map file is
5) type: map2dif mymodel.map
where "mymodel" is the name you saved your .map file as.
then take the .dif file and your textures and package them up like you would any other addon.