up front, I am not an Excel expert...
am not sure if this can be solved within the current Clipboard Help and Spell.
under "Modfy Format/Case" one can add \n to lines but not to words.
Anyway, a suggestion only...
I would download a named ASAP Utilities at: http://www.asap-utilities.com/
basically it is free
".. you are hereby licensed to use the SOFTWARE without charge in a non-commercial organization or for home-use.
To avoid the use of obsolete SOFTWARE each unregistered version will display an update notice 6 months and expires 9 months after its release
It installs a plug-in with a lot of handy features.
Within ASAP this is really a piece of cake:
Click ASAP tab
, then select Columns & Rows
and then Merge row data, separated cells by a line break
Maybe this is what you are looking for?
=Find and Replace Preset