Excel while you are typing is in 'Edit Mode' and very little can be done
with it, hence it doesn't work like Word for example. I think any kind of
coded resolution would either not take you forward or be annoying

1) You could have code under a button to spellcheck, but why then not use
the built-in
2) You could have a worksheet_change event, but that would trigger a spell
check after you exit every cell (unless you program some out) and could
become annoying

Back to you if you want either of the above, post back