http://sourceforge.net/projects/tcljava/ is the home for this software. There is an active mailing list at this site for questions and support issues.
TclBlend is a Tcl extension which, with appropriate setup and auxilarly tools, allows one to call Java classes from Tcl.
Requirements include a recent version of Tcl compiled with threads and a recent version of Java.
Note that TclBlend is an extension which requires a number of environment variables to be set. That is why the TclBlend community recommends using a script that comes with the extension which is designed to set all the various variables before invoking tcl.
http://softwaredev.earthweb.com/sdopen/sdososj/article/0,,12421_630531,00.html is an article by CL on TclBlend and Jacl.
One comp.lang.tcl poster reports satisfying light-duty use of JDBC with TclBlend.
See also Jacl - Java and Tcl - Tcl and other languages, and CL's personal notes on TclBlend [L1 ].