I've always just done it by hand. It's easy (for me anyway) to follow along 1/4-1/2" from the line. You can also give yourself deeper SA's if you like in areas you question the fit of.

The hard part is following the line itself, when it's nested w/a lot of other pattern pieces, it's difficult for me to follow the right color sometimes.

Burda has such a good sloper, esp. in slacks. One of my fav. skirts is a Burda pattern, too. Good luck, hope your friend's skirt comes out nice!

The link has some great tips that may help.

Here is a link that might be useful: patternreview.com thread on Burda

I have a sewing gauge and one end is exactly 5/8" wide which can be just laid down next to the pattern piece and use it to mark a dashed line where you want to cut.

Thanks, Annie--I'l have to look at my sewing gauge more closely!

Most measuring tapes are also 5/8" wide as well.

Rosefolly, I didn't know that! I'm going to check mine all tonight!

Look what I found! It's a little magnet marker that you stick onto your scissors. And then you align the black ring with the sewing line, and cut.

Nancy's Notions is the only place I've found them.

Here is a link that might be useful: Seam Allowance Guide at Nancy's Notions.

And Clover makes a double tracing wheel--

Here is a link that might be useful: Double Tracing Wheel

There's also a Traum Tracing Wheel--vintage, so you'd have to get it on eBay or somewhere like that.
http://sewcraftful.com/tools/10giftideassewer/

Here is a link that might be useful: a list of gadgets--pic of the Traum Tracing Wheel among them