Could not install the HTC IME keyboard



I am trying to install HTC IME keyboard on my HTC Desire. I want to add to the keyboard some unicode characters that are not on the default keyboard, and from what I read, that in this updated version is indeed possible.

I've got HTC_IME.apk from Download: HTC IME Keyboard v19 | Droid Life: A Motorola Droid Blog , and installed the Astro application manager on the phone.

However, I could not install the new HTC_IME.apk: when I select it in Astro, I get to choose between three choices: UnInstall, Upgrade, and Launch. Upgrade starts kind of hopeful, but after some time fails with "Application not installed" error. If I'd go and try to uninstall (from what I understand, that would be the existing keyboard version that would be uninstalled), I get "Uninstall not successful".

I guess I have no privileges to do what I want, but I kind of dont want to root my phone, at least not yet.

Any ideas what can I do to fix this?