I use a macro for such comments. It's not exactly as you're asking for, but gets the same end result. What I do is type in the comment starting at the left edge of the text area, select it, then run the macro. It inserts the stars and indents appropriately. Here is the macro:

/*
* DocComment.bsh - a BeanShell macro script for the
* jEdit text editor - puts the selected text in a JavaDoc-style
* comment block
* Copyright (C) 2002 Dale Anson
* danson@germane-software.com
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with the jEdit program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
*/


void docComment() {

// check buffer read-only status
if ( buffer.isReadOnly() ) {
Macros.error( view, "File is read only." );
return ;
}

// get the current selection or the current line if no selection
Selection[] selections = textArea.getSelection();

// this doesn't work right with multiple selection, so don't do anything
if ( selections.length > 1 ) {
Macros.error( view, "Doc comment does not work with multiple selection." );
return ;
}

String ls = buffer.getStringProperty( "lineSeparator" );


// make sure last line ends with a line separator
String line_text = textArea.getLineText( textArea.getLineCount() - 1 );
if ( !line_text.endsWith( ls ) && textArea.getCaretLine() >= textArea.getLineCount() - 3 ) {
buffer.insert( buffer.getLength(), ls );
}

// if nothing is selected, select current line
if ( selection == null || selections.length == 0 ) {
int line = textArea.getCaretLine();
selections = new Selection[ 1 ];
int start_offset = textArea.getLineStartOffset( line );
int end_offset = textArea.getLineEndOffset( line );
selections[ 0 ] = new Selection.Range( start_offset, end_offset );
textArea.addToSelection( selections[ 0 ] );
}

// adjust the start and end line offsets to reselect after the move
int startLine = selections[ 0 ].getStartLine();
int endLine = selections[ 0 ].getEndLine();

// insert stars
for (int i = startLine; i < endLine; i++) {
buffer.insert(textArea.getLineStartOffset(i), "* ");
}

// insert start and end of comment
buffer.insert( textArea.getLineStartOffset( startLine ), "/**" + ls );
buffer.insert( textArea.getLineStartOffset( endLine + 1 ), "*/" + ls );

// indent lines
buffer.indentLines( startLine - 1, endLine + 1 );

// insert spaces so the stars line up nice
for (int i = startLine + 1; i < endLine + 2; i++) {
buffer.insert(textArea.getLineStartOffset(i), " ");
}

// reselect the changed text
textArea.selectNone();
selection = new Selection.Range(
textArea.getLineStartOffset( startLine ),
textArea.getLineStartOffset( endLine + 2 )
);
textArea.addToSelection( selection );
}

docComment();