[hypoxia]

The data wiring simply keeps each wire at the same orientation on the plugs, ie the black wire (and the other colors) is in the same position at both ends of the cable when you place the RJ11 plugs beside each other.  When you make a cable using your Cat5 wire you keep that same orientation so the finished product has the same colors when you put the two ends beside each other.  It doesn't really matter what the colors are as long as the end result is having those colors in the same orientation.

It is best to make the wiring extra long.  Those RJ11 connectors are susceptible to corrosion and will eventually have to be replaced if exposed to moisture/humidity.  I carry spare RJ11, RJ12 & RJ45 connectors along with the crimping tools to make those repairs.