The problem with that is the cable tie might try to come out inwards. If the channel was open at the top or bottom, it would be more likely to stay in the channel because the cable tie wants to go straight?
With the right design of tool and length of tie, you could have the catch end of the tie held in place and you then just need to guide the open end though the catch then once through, lift / drop the tool off.
Well, if you don't make something, Dragons Den here I come. ;-)