It sort of depends to what you mean by "easy", and of course it depends greatly on the format of the source files. For example, I was working on importing the Cotton Patch Version into Accordance - formatting its verses for Accordance was quite easy, but it combined multiple verses regularly, and that is requiring line by line checking.
But, lets consider your example, the online WEB. I downloaded the USFM version, and its text files appear to be fairly close to what Accordance would need. As Julie said, this is already available in Accordance, but to use it as a test version, here's the rough steps required:
0) Before you get started, you're going to want a good text editor. TextWrangler is a fantastic free one, and what I use, but I'm sure there are probably others. You want a text editor that does raw text (so not TextEdit, which adds styling), and allows grep/regex (more on that in a second).
1) First, Accordance is expecting one file, so you need to merge all of the different books into a single text file. You can probably find a utility to do this, or just copy/paste.
2) Be sure the file uses Mac linebreaks (CR, not LF), and is in MacOS Roman Encoding, or UTF8 as necessary.
2) Remove all the extraneous information from the file. Any stuff with the \toc tag looks to be unnecessary, the \id, the \ide, maybe others. These seem to be 1 per book, which you can do by hand, or use a regex!
Regex, similar to grep (not 100% the same, but close enough for our purposes) is short for Regular Expression. Its a type of advanced text search and replace. It is used heavily by our module developers in developing their tools, but also used by many, many other people in almost all computer professions. It lets you do searches like: 'Find everything that looks like 'Line1: [some word] [some other word] [some number]' and turn it into '[some number] [some other word]'. Its the most powerful, and easiest way to do the type of massive textual edits you want to format some text, without going line by line. You can find lots of tutorials online, or within the TextWrangler help under "Grep reference".
3) Now using regex, you'll want to clean up each verse and chapter number to follow Accordance's expected format.
4) At this point I'd start trying to import the file into Accordance to see what type of errors are left, perhaps some oddly formatted characters, some extra characters you missed, or something else.
Afterwards, be sure to post it to the Accordance Exchange if you have the rights and want others to be able to use your work!