Adam joined Rangers aged 15 in December 2000, making his debut just over three years later, but was sent out on loan spell to Ross County and St Mirren before returning for a further two and a half years ahead of his move to Blackpool and this summer's switch to Merseyside.
"[There were] ups and downs really. I had some great times there but also some hard times and that was with not playing, which was a difficult period," said the Scotland international.
"That's the way it goes sometimes and football changes so much nowadays.
"I'm glad I started there and the coaches I had over the years helped me to progress to where I am today.
"But the friendly is certainly one I'm looking forward to because it's not very often you get the opportunity to go back and play against your former club."