Well. The question is about TCL and not about perl. More than that, it is about interaction of TCL with shell :) Anyway. I don't believe you need such a "dot-command" for executing TCL. It is always executed in the context of the current shell. Just make sure you export the desired variables, or add them to the command line. For example

bash$ MY_ENVIRONMENT_1=some_val MY_ENVIRONMENT_2=other_val ./my_tcl_sc
+ript
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The "dot-command" for shell is needed, because otherwise new shell interpreter is started. The #!/bin/sh on the first line of the script requests this. In TCL scripts (as well as perl scripts) the first line requests some different executable, not the new shell (normally) so, no new shell is started.