Lets assume you start with your antenna pointing north, and it will turn counter-clockwise as you look up at it (business end swings to east). NOTE: Before you put the mast up connect the rotor and rotate it fully clockwise (looking at it from the bottom) to be sure it is set up this way or it might turn the other way.
I would bring the cable up the south side of the mast and have it pass to the east of the mast around to the antenna connector on the north side. This assumes the connector is on the director end of the antenna (not always true).
Now when the antenna rotates (to the east) it unwraps itself from the half wrap as it points south then re-wraps itself a half wrap as it moves back to the north from the west side.
This way the cable can never be wrapped around the mast more than one half way (rotators only travel 360 degrees not beyond that). Leave enough slack in the cable so it NEVER even begins to become tight no matter which way the antenna turns. The cable should also be supported solely by some type of stand off or other mechanical means, so that the electrical connection on the end bears NO weight at all.
I must also assume that since the mast is 150 ft from your house, you are using a pre-amplifier. That long a run will lose you a lot of signal - Oh, and NEVER use RG-59 on such a long run - ALWAYS at least RG-6.
And install a grounding block before the cable enters your house (none of that nasty lightening needs to come in).
Yes, you can splice the rotator control cable, but it might be better to locate a longer length (it is sold in spools of greater than 100 ft.). If you splice it, be sure to solder the connection and tightly wrap each wire connection in electrical tape or in some other way weatherproof that joint.
Enjoy!!