This ZIP contains the converted high-res tiles for WHAP's WIA addon. It also includes a modified base config (to remove the now superfluous high-res tile definition). In addition, there is a surface flattening file to make 20km around the base MSL0, so the old definitions of base elements match up again.
You will need D3D9Client 4.9 with activated terrain flattening and linear terrain interpolation (instead of cubic) to see this last bit, though.
The conversion is not perfect, it was an automated run with treeman's -b option. It was done on stock surface and mask trees, no clue how it would perform with high-res trees.