Custom offsets for x axis labels.

[jeppester]

I'm am building a chart where x is the time, and y is a score.

|                  ______________
|  _______        /              \
| /       \______/                \_____
|/                                
|_______________________________________
     |           |         |          |
    Jan         Feb       Mar        Apr

I want to have a label on the x axis for the beginning of each month.

Is there a way to specify a specific x-coordinate for each label on the x axis?
I'm aware that if there are an equal amount of data point and labels, then they should align, but in our case there will be many more data points than labels, so as I understand the documentation, the labels we specify will be evenly distributed.

Since months are not equally long, having equally distributed x-markers is not suitable for our usecase.