If you haven’t already spotted this, similar to the HTC Desire S ICS update RUU, the HTC Rhyme ICS update RUU has also been uploaded on HTCdev.com. It is unlikely that HTC will be releasing an OTA update for Rhyme, so this is your last resort to get Ice Cream Sandwich on your Rhyme smartphone.
This RUU is for the EU and WWE (Worldwide English) versions and is 456.7MB in size.
Installing Ice Cream Sandwich update via RUU is pretty simple. All you have to do is install the device drivers if they are not already installed. Then connect the phone using USB cable to the PC and run the ROM update utility. (Make sure to take backups of everything.)
After the process is finished, you are will on the Android 4.0 with Sense 3.6.
(Direct link to RUU)