Printing standards don't describe the desired printing condition / target curve for spot colors. As a workaround the black press compensation curve is usually used. But if preferred one can also create a custom press compensation curve for (specific) spot colors.
Print the Esko spot control strip (available here: "x:\bg_prog_intellicurve_v1x0\dat\doc\ESKO_Spot_Control_Strip_Sep_value.pdf").
Make a copy of the layout file for this strip: "x:\bg_data_intellicurve_v180\ESKO_Spot_Control_Strip_Sep.it8".
Open the it8 file with a text editor and define the spot color name in the PROCESSCOLOR_ID line. Here is an example for PMS200: "PROCESSCOLOR_ID "pms1000c/200"
Save the it8 file and rename it, refer to the spot color (e.g.: ESKO_Spot_Control_Strip_Sep_PMS_Coated_200.it8).
Open the PressSync curve set.
Open the setup window.
Click the Spot Colors tab.
Click the + button and add the spot color for which you want to create a compensation curve.
Select SCTV as measure unit and Linear as the desired curve.
Although this is the recommended setting for spot colors, any other measure unit and desired curve can be selected!
Click the OK button and save the curve set.
Go to Measure > Measure Automatic.
Select the layout file you created in step 2 (e.g.: ESKO_Spot_Control_Strip_Sep_PMS_Coated_200)
Measure the spot control strip.
Click the Go To Results button.
Click the Spot Colors tab to see the calculated compensation curve.
Click the Save... button and choose Save curves.
Save the curve set.
Select the PressSync curve set as Default Press Curve in the Separations settings of the Image to Screened Separations ticket.