i wouldn't need lotion to make cum just your bare heel rubbing my penis, if you want to put lotion on your heel just out of the reach of penis, fine, your foot would have a routing section.
I want your foot to be standing on my cockhead while it cums not letting the semen out, then once the ejaculating has stopped and time has passed, i'd take your foot of my penis, drain the semen into my hand, put your foot back on my cockhead and rub the semen into your foot.
website - http://www.theback40foot.com/home.html
news story - http://www.kptv.com/news/18151210/detail.html