I'm not a professional (magician)!
There is another reason this is bad idea: in many effects, the card that is being hidden changes during the effect, so having roughing fluid on some of the cards would not be helpful.
If you want to get the hang of the two-card push-off, forget the Elmsley count and learn Edward Victor's "E-Y-E" trick. It uses just 3 cards.
Also, it is possible to do the Elmsley Count as well as other counts (e.g, the Jordan) without any 2-card push off at all.
Try this as a Jordan Count:
1. Use 4 cards. 3 are face-down and the 4th card, the bottom card of the packet, is face up.
2. Hold the packet in a right hand Biddle Grip.
Use the left thumb to pull the top card into your left hand.
3. Use the left thumb to pull the next card into your left hand but hold a left little finger break under it.
4.Take the next two cards as one card and at the same time steal back the broken card.
5. Take the last card.
It's a bit difficult to explain this without pictures. Back in the mid 70s, I worked out ways of doing all of the usual counts (Elmsley, Jordan, Hamman, 2-as-4, etc.) from exactly the same grip with no push-offs, etc.
I published one little bit of this in Pabular, but I don't remember where.