Hi - I don't have the exact answer since I've not done it before but this may be of assistance.
http://sharpkit.net/help/SharpKit.ExtJs/Ext.panel/PanelConfig/
I've only found this and started playing with it last night. I believe tools option is what you may be after.
I was playing around and was able to only show refresh icon for example. Basically I think you'll have to have something in the advanced section of the form and put the logic for help in it.