Thanks again to Gadi for this info:
Bus mastering DMA support for the Intel TX chipset is available in 2.0.31
and above.
In older kernels (such as Slackware 3.4's 2.0.30), the controller will be used in the slower EIDE mode. In either case the controller will be automatically detected by the kernel and you should have no trouble using it.
Full UDMA support for the TX chipset is included in the UDMA-Generic patch.