How is this?
setm(gca,'plabellocation',10,'labelrotation','on')
The 'plabellocation' is poorly named, but it means the spacing of latitudes (p for parallels). The 10 value for 'plabellocation' places lines every 10 degrees latitude. The 'mlabelrotation' rotates the labels around the circle to keep them from conflicting with the outside of the axis.
A note: the default coastline in Matlab is not really a coast line, and it's also not really a grounding line. Take a look at the Ross Ice Shelf, where the coastlat and coastlon appear to follow the grounding line, but on the Filchner Ronne Ice Shelf it follows the edge of the ice. Amery and George VI are also a bit wonky. You can simply type
bedmap2('gl')
Or
bedmap2('coast')
to get more accurate outlines of the continent.
