Stop worrying - the lack of a string or two will do nothing to harm a neck. All this business about locking on strings is un-necessary. I've never done it and I've been changing strings for over 40 years.

Simply attach the string to the bridge end and line up the hole in the tuner roughly with the path of the string. Pass the string through the hole and put a capo on at around the fifth fret to hold things in place. Grab hold of the string at the nut and pull it back out of the hole by around one and a half to two frets and bend the string behind the hole by 90 degrees. Wind on the string trying to keep the windings even and bring it up to pitch. Change them one at a time and once they're at pitch stretch them and bring them back up again.

The one and a half frets isn't crucial - what you're trying to achieve is a similar and sufficient amount of string to give enough to wind onto the stringpost (3 or 4 turns but possibly more on the top E and B) The more you do it the easier it becomes.
Ray