1. As peer my legal knowledge, POA can be executed from abroad even on plain paper.
2. The said POA shall have to be signed before the appropriate officer of the Indian Consulate who shall have to append his signature duly vetting the vetting the signature of the issuer of the POA.
3. The said signed and vetted POA shall have to be sent to the POA holder in India who shall have to preserve the envelope carrying the said POA and then get affixed Rs.50/- stamp on it from the local Stamp Commissioner.
4. having stated the above, I always send the POA to my clients staying abroad printed on stamp papers dulky following the rest of the procedure, jus to avoid any objection from other side lawyer who may not be aware of the legal procedure and start objecting if the POA is not printed on Indian stamp paper.