Problem : using glTexSubImage3D with borders

I am trying to use texture bricking for my volume rendering application. The whole volume data is divided into 3D bricks of smaller dimensions so that they can fit into the texture memory. Also since I am using Linear filtering I get a black border between the two bricks if I dont use an extra voxel from the neighborhood. Thus in short every brick is made up of its own data plus a adjacent voxels along the border.
Given this, Now I am facing a problem where I can no longer use glTexSubImage3D to replace one texture brick with another. I use this function because all bricks can not be loaded completely in the small amount of texture memory available. But the glTexSubImage3D doesnt take the border size as the parameter. My border is of size 1 and my data is also of appropriate size(actual size + 2 /for borders/). Consequently I had to use glTexImage3DEXT in place of the SubImage3D but that slows down my application quite a bit.
Can someone please suggest an alternative.
Specifically My question is :
How to use glTexSubImage3D to replace a 3D texture with border of size 1 with another 3D texture with border of size 1?

Thank you.


Answered in the advanced forum.