Note that 8.4.13 is not the old "Batteries Included" series. I believe it includes only TCL & Tk 8.4.13 + Tiles. From my experience, if you install this or use the TclTk built into OS X on an Intel machine, you will not be able to use old Tcl add-on packages that have a binary component (.dylib) since they are PowerPC binaries. Rosetta doesn't kick in for plug-ins and interface with a native Intel binary.

You might be better off sticking with an all PowerPC installation if you need a library that's only in the BI distribution or check out the ActiveTCL package. It has many, but not all of the BI packages in them and is available for Intel and PPC. Fink is also an option to bring your whole Tcl install together on your platform.