I hope you like raglans, because Walker is really the only choice if you want instructions for top-down and seamless patterns other than raglan or yoke sweaters. Her book is very unique in that respect, and no one whom I’m aware of (and I researched this pretty thoroughly last year) has done work in that particular area.
If raglans are okay, there are lots of patterns out there, many free. Here is one pattern generator you can try, though that particular pattern doesn’t include any short row shaping to make the neck lower in the front than the back – which can be a bit stifling if you want a crew neck. This one requires a little math, but includes the neck shaping. I’ve seen similar instructions in Vogue Ultimate Knitting and various sweater design books, too. It’s a pretty basic pattern, though individual “recipes” might vary a bit in the percentages they use. One book you might want to take a look at is Ann Budd’s The Knitter’s Handy Book of Sweater Patterns which includes a lot of other kinds of sweaters you won’t be interested in (most are seamed), but which does have a section on how to incorporate stitch patterns into the basic designs, which can help you figure out how to do the lace.
If you ever want to venture out of the world of raglans, do look at Walker again. If you’re really having trouble following her, you might want to take a look at Maggie Righetti’s Sweater Design in Plain English – she’ll give you both a conceptual and technical understanding of traditional sweater constructions of all types – reading through her book a few times might give you a foundation that’ll help you better understand what Walker’s trying to accomplish.
Ah, I should mention one more thing… when it comes to percentage systems, don’t always expect a perfect result – they’re based on averages, so if you don’t have an average body, you might want to make some adjustments. The same thing goes with yarn… because the percentages are based on averages, if a particular yarn has a stitch gauge to row gauge ratio that strays far from the norm, you may have surprising results. But for the most part you should be okay.
ETA: Now that I think about it, the raglan in the Budd book might be bottom-up… unfortunately I borrowed it from the library so I can’t check for you. Maybe some one else can confirm.