You will have to unbound the combo box and use code in an afterupdate event to perform the update back to the table. After updating the table, you will have to requery the combo box to reflect the new data.
You should be able to perform the update using DoCmd.RunSQL or a DAO.Recordset object. The latter doesn't trigger a warning message box.
Todd Sutay's solution sounds fine but if you don't want to unbind your combo box there is a programmatic solution, albeit somewhat messy. I should add that if your form (as well as the combo box) is bound to tblICL1 then I would not use my solution since you will possibly experience record updated by another user and other fun messages. You can avoid these messages by issuing a me.undo but of course that simply resets any changes the user may have made elsewhere on the form.
OK. Choose a way to invoke the edit process. This could be by trapping the double-click event for the combo box itself or by covering the left side of the box with a transparent command button. When the event occurs use an input box to prompt for the edited value, using the current value as the default. If the user changes the value then perform all necessary validation checks before pasting the new value to tblICL1 via an update SQL query. Finally requery the combo box.
If you want to be really clever then set the combo box to the new edited value as this puts the user back where he/she started but with the change shown.
The form is not bound to tblICL1 so I guess your method would work. I don't quite understand what you are saying. Would it be possible if you attached an example of this so I could look over it or explain it a little further?
The best I can do is construct an example. If you send an email to email@example.com or firstname.lastname@example.org I will send you an .mdb file as a reply. However I use Access 2002, so if you use an earlier version I'm not sure if you can open it.
Failing that I can post or attach some event code for you.
One final question: do you use much VBA code? If so do you use DAO (Data Access Objects) or ADO (Active X Data Objects)? You of course may use neither and communicate with the Jet database through macros, queries, etc.