Lockbacks and Compression locks can be done the same way...
finger into kick area(unsharpened bit where the stamp and all goes), thumb the lock closed and flick your wrist. The kick hits your finger, and then you can flip it over and thumb the blade close(makes a comp lock leftie friendly).
comp locks you could also thumb lock closed and index the hole closed(I do this and it works).
As to liner locks(even with my millie), just get leverage, thumb lock, hold liner, and index the spine till the kick hits your thumb, then put thumb onto hole and close.
the thumb and flick is the safest way I've found for lockbacks.