While there are not a lot of custom kernels out there at the moment for the HTC EVO 4G LTE, it’s been reported that it is no longer possible to flash kernels in standard recovery mode after the last update, meaning if you want a custom kernel you’ll need a recovery with Smart Flash/Dumblock/similar capabilities, flash from Fastboot, or Flash Image Gui.
I used Flash Image GUI in extensive testing on the HTC EVO 3D and never had an insurmountable problem with it, so hopefully that reliability will translate over to the EVO 4G LTE.
Flash Image GUI is $0.99 from the market and worth it.
Download: Google Play