If Line6 only allows EX1 pedals, they should it deliver with their PODs.
If they don't want to support other pedals, what I understand ;-))), they should
provide all necessary technical information about EX1 (R, pinning, pot specs etc.)
Technicians know how to handle it, others ask or ..... buy EX1, no drawback for Line6.
To play a open game always counts.
Have a look at:
http://www.harmonycentral.com/t5/Effects-Pedals-Multi-Effects-and/Expression-Pedals-and-their-Pot-Values/td-p/30347097
Frank