Rich,
I'm not sure about modification of the cell comments, but in case there is no way of modification, here's an option.
Set up a "context-sensitive HELP function" with the following steps:
1) Create a range name for each of the cells where you want the user to be presented with a comment or message.
2) Create a macro and attach it to a HELP icon, or to a macro BUTTON, and/or to a "hot key" - example <Control> H.
3) Depending on the size of your application, you might want to have the macro start by checking to see which sheet the user is on, and then have the macro branch to a subroutine which has code which will display messages for that particular sheet.
It would be something like this:
main routine:
{IF @CELLPOINTER("sheetname"

="intro"}{h_intro}{RETURN}
{IF @CELLPOINTER("sheetname"

="data"}{h_data}{RETURN}
etc.
etc.
h_intro (subroutine)
1st line:
{IF @CELLPOINTER("address"

=@CELL("address",cur_date)}{LET title,"CURRENT Date"}{RECALC lmf}{EDIT-QUICK-COPY textrange,date_txt}{DIALOG largemess}
2nd line:
{IF @CELLPOINTER("address"

=@CELL("address",input_1)}{LET title,"Title Related to input_1"}{RECALC lmf}{EDIT-QUICK-COPY textrange,date_txt}{DIALOG largemess}
Unless you've had a little experience with macros, you might be a bit intimidated by the above. However, with a little effort, you should be able to set this up.
If unfamiliar with DIALOG boxes, try using Lotus 123's HELP function, and DIALOG Editor to assist in setting up the DIALOG.
The benefit of this option, is that you'll be able to have messages which will FILL THE SCREEN, so the user will DEFINITELY "get the message".
If you like, I could email you an example file. Just email me, and I'll attach a copy via return email.
Just one word of caution... I'm using Lotus 123 Release 5.0, so I hope your version can accommodate the same code.
Regards, ...Dale Watson dwatson@bsi.gov.mb.ca