I have tried substituting rubber legs for the pheasant. They are much easier to tie in a knot--not least because you can just pull off a long strand, tie your knot wherever, and then cut them to length. However, they do not look as natural as the pheasant, and they (the rubber legs) require some finesse with thread tension to keep them from splaying out too far from the body of the fly. Of course, we all know that sometimes flies that look anything but natural end up catching the most fish, so, I suppose, that shouldn't necessarily be a deterrent to you using the rubber legs.
If you really want to do the pheasant legs, and IF this is to be your one-and-only time tying this pattern, then I would second BobHRAH's suggestion of just buying some pre-knotted pheasant legs. It will save you a lot of frustration. If you really want the pheasant legs AND you want to knot them yourself, you really need to buy the tool that's made for the job. It's basically just a tiny latch hook tool; I imagine you could find one that would suffice at a craft/sewing store like Jo-Ann Fabrics or similar.
"... trout do not lie or cheat and cannot be bought or bribed or impressed by power, but respond only to quietude and humility and endless patience." -- John Voelker (aka Robert Traver), Testament of a Fisherman