well you can't do it within bsp direct without making a DLL within C/C++ that can alter the render of the textures once projected onto the bsp world, which would require knowing the render setup within the DBpro DLL which handles the bsp...
Althought Lee would probably be willing to show an example of howto access it, then getting in an bump mapping of this nature would be very tricky and not recommended until DBpro is more stable itself!
However if you develop the world as a form of BSP which is rendered within DBpro itself - then to bump map a surface is quite a simple matter, yet the calculations are complex and very processor consuming
if you really want to achieve it then i'll see about writing up a small demo of bump mapping...
but please make sure you have the rest of the game done and this demo will only help for you to understand how bump mapping works not howto achieve it as a plugin for bsp!
Holy jumping mother of god NOOOO!!!...
Ahem I mean, I'll think about it