Georeferencing Maps in Arcgis

Entering specific x,y coordinates when georeferencing

In ArcMap, add the layers residing in map coordinates and the raster dataset you want to georeference.
Adding the data with the map coordinate system first is a good workflow so that you do not need to set the data frame coordinate system.

If you do not have a dataset with map coordinates, then you must set the data frame coordinate system before continuing.

To display the Georeferencing toolbar, click the Customize menu, point to Toolbars, then click Georeferencing.
In the table of contents, right-click a target layer (the referenced dataset) and click Zoom to Layer.

Click the Add Control Points tool Add Control Points.
Click a known location in the unreferenced image to add the first coordinate in the link.
Right-click the image and click Input X and Y.
Type the reference coordinates on the Enter Coordinates dialog box.
Click OK.
Scanned paper maps, drawings or maps found online may contain useful information not found elsewhere. GIS allows us to georeference a map to link the image its corresponding location. This video tutorial shows the steps to complete the georeferencing of a map with ArcGIS.

[astarothen]

Suggestion on how to do the same when you have decimal degree coordinates map? (I tried several time but it doesn't work).
No problem with kilometers or DD°MM"SS' but it is a mess with xx, yyy°