So it looks like it may not be possible for the Home Tab to show "All-Day" appointments without CHT installed. If it is possible it's not a mod that's been shared a lot.
Because it was brought up, I assumed that other ROMs had this "feature" as MWalt2 called it. According to MWalt2 HTC did away with that "feature" some time ago. So I'm assuming that it's not a bug and that in fact not many, if any other ROMs out there will show "All-day" appointments on the home screen without the addition of CHT.
If you're interested, check out this thread I started at XDA Chef Central to try and get some help on the matter. It's not a lot of reading, only 3 posts.
[Q]All Day Appts. not showing on Sense 2.5.20XX Home Tab - xda-developers
Thus far, MWalt2 has never steered me wrong and always knows what he's talking about.
If anyone knows of a ROM that shows "All-Day" appts. on the Home Tab without the use of CHT, please let me know which/who's ROM so I can solicit help from them.
Otherwise, I'm leaving this
"bug"/missing feature alone.