What is the equivalent in cups for the 1 - 2 lb bag 10x powdered sugar of Nicholas Lodges tylose gumpaste recipe?
I am not sure what 10x means. I think 3 ½ cups of icing sugar is equivalent to 1 lb sugar, I think...not sure.
Also, I do not have a Kitchen Aid mixer or any kind of heavy-duty mixer, I have a hand mixer.
Will the hand mixer work? I was thinking that I could use the hand mixer up to certain point in preparing the gum paste, and then use a wooden spoon to continue.
Any suggestions will be appreciated.

I have found it really is better to weigh the powdered sugar for that recipe. You can buy powdered sugar in a 2lb box or bag if you don't have a scale. I am not sure of the cup conversion. It depends on how much packs into the cup with each scoop.
I think the recipe comes out better when you weigh it. I have also found that you may have to adjust the amount of sugar you leave out if you have extra large egg whites. It isn't an exact science. After mixing the whites and sugar, it should look very fluffy and whipped. Sometimes I have to leave out some sugar too. You can always add more sugar to make it more stiff. It is hard to adjust by adding whites it if it ends up too stiff.

You could use the hand mixer to mix the egg white and sugar and then add the tylose and mix with a wooden spoon.
HTH!

Powdered sugar is just pulverized granulated sugar. Older cooks and cookbooks refer to powdered sugar as 10X sugar- meaning it's 10 times finer than granulated. Even regular powdered sugar should be sifted, even twice until it's VERY fine in his recipe.