According to the web page above... PostgreSQL 6.4 release has a minor bug. I does not includ by default the crypt lib when compiling libpgtcl. So, you will need to manually add a -lcrypt to SHLIB line in Makefile in src/interfaces/libpgtcl and then make clean and make again. The new libpgtcl.so library is properly configured to run pgaccess.
*** This bug has been marked as a duplicate of 2698 ***