georeferencing tiffs & Jpegs

I have geo referenced tif & jpgs I also have the twf sister files In the TWF
file is the coordinate of the top left hand corner insertion point but not
the size or bottom right hand corner.
So how do reference the images with the right projections and coordinate
systems from the twf files?
In other cad packages ie microstation the the process is automatic as it
reads the twf file and inserts the image /raster aerial photo automatically.

 

In the downloads section on the ER Mapper site:
http://ermapper.com/download/ are free ECW plug-ins for R14 -2002 that also handle other georeferenced images, along with image + world file combos.