Chris D'Iorio's List: TiddlyWiki

The NewTiddlerWithFormMacro has a var tags statement in the code about
the 8th line from the bottom.  You can add the tags in there if you
want.  Since I have multiple forms, I duplicated the
NewTiddlerWithFormMacro for each form I use where I need custom tags
applied...just adjusting the tag statement near the bottom and of
course the macro and handler name.

I managed to get this to work by hacking the newTiddlerWithForm macro
in the FormTiddlerPlugin from "http://tiddlywiki.abego-software.de/
#FormTiddlerPlugin" to allow a new parameter that provides a tag to be
used by the new tiddler.

at the bottom of the Parsing section, after it says:
 if (i < params.length && params[i] == "askUser") {
 askUser = true;
 i++;
 }

Add in:
var newTag = "";
 if (i < params.length ) {
 newTag = params[i];
 i++;
 }

and towards the end of the Processing section, where it says:
var tags = [];

Add in:
if (newTag) {
    tags[0] = newTag;
 }