[TxMt] How can I make every file in a given (project) directory use shell script syntax highlighting

Hi folks:

I am new to textmate and to the list. I have spent awhile with the manual but either I missed this or it is not in there (or maybe it can't be done).

I keep all my zsh configuration files in /Library/init/zsh

These include various files that are sourced, as well as shell script/ function files. Since the latter have #!/bin/zsh at the top, textmate does the right thing, but I would also like the other files, that set up my environment, define aliases, and so forth, to use the same syntax highlighting, even though they do not have #!/bin/zsh at the top.

Is there a simple way to do this?

Thanks.

Bill