I Googled it in Japanese.
Explanation page with download link:
VOCALOID4 Editorで巡音ルカV4XのE.V.E.C.を使うjob Pluginについて:きょん☆さんのブロマガ
Actual download link:
evecEditor160917.zip (evecEditor160917.zip) ダウンロード | きょん☆さんのアップローダー | uploader.jp
Click the button under the MD5 link that says "ダウンロード". It will take you to a new page that takes several seconds to pop up your zip download (so don't panic if it seems like nothing is happening).
Other explanation link:
先日公開した巡音ルカV4X用Job Pluginで作成したVoice Colorを変更するJob Plugin:きょん☆さんのブロマガ
After unzipping, open Vocaloid Editor.
Job > Manage Job Plugins > Add > find the folder you downloaded and the plug-in will be a .lua file (there are 2, EVEC_Change.lua and V4X_EVEC.lua). > You have to add each of these one at a time (so click the 1st one, click OK, click Add again and select the next one).
Highlight the notes you need to put EVEC on. I don't have Luka, so when I got to Job > Job Plugin, all I see is "EVEC Change".
When I use EVEC Change (I'm using it on Len Power), a popup appears.
The Voice color options are:
なし nothing
Soft (might be different for you)
Power (might be different for you)
削除 delete
母音に戻す return to vowel (don't know what it means, I don't know how to use EVEC)
Color Release 部分 = color release part
Voice color ノートをプロテクトする = protect voice color note
この設定値をデフォルトにする = return these settings to default
If you have more questions, feel free to ask. I literally didn't know this plug-in existed and just installed it now.