What about mixing it into something like plain chicken baby food? I can pretty much give my cats anything when it's mixed with baby food. You can also get glucosamine/chondroitin/MSM in powder form, although I understand wanting to use what you've got rather than having to buy another product.
"To close your eyes will not ease another's pain." ~ Chinese Proverb
“We must not refuse to see with our eyes what they must endure with their bodies.” ~ Gretchen Wyler