Soldering is required. For me it's not really the soldering part that's a pain, it's the desoldering.
The only way you can switch them without desoldering is if the switches are PCB mounted. I don't know of any tenkeyless that are PCB mounted. : (
BTW, if you're looking for a tactile click, clears aren't what you want. clears have no click, only a bump.