The menu system of WinEdt has changed a lot since that package was crafted, so whilst the installer places the macros and images in reasonable locations, it cannot integrate itself to the menu as it once did.
It requires a specially modified approach, where we add one extra customised
Diagrams menu section after
AMS NOT =<> in WinEdt gui.ini based in principle on the old xy.gui
There are some unfinished issues to address, see how the older large icons do not look right using the old icon values, so there are some unresolved issues to be investigated, OR make extra icons to suite NOTE the old icons are in one folder, newer icons are in 3 sizes ?
It involves a fair bit of repetitive editing, and I used find/replace so will just simply provide the modified section for you to test.
ITEM="Rectangular (n x m), Xy-pic"
ITEM="Lift Square, Xy-pic"
ITEM="Top Triangle, Xy-pic"
ITEM="Left Triangle, Xy-pic"
ITEM="Right Triangle, Xy-pic"
ITEM="Top-Right Triangle, Xy-pic"
ITEM="Lower-Right Triangle, Xy-pic"
ITEM="Lower-Left Triangle, Xy-pic"
ITEM="Top-Left Triangle, Xy-pic"
ITEM="Exact Sequence (n), Xy-pic"
ITEM="Commutative Diagram (n x m), AmSTeX"
Where to add the new menu (Infographic with instruction below)
1) Open Option Interface and Locate tex symbols section in your gui.ini (it is highlighted in my picture on left)
2) Right Click Open
3) Recommended File Save Copy as gui.ini-backup (anything that you will remember later)
4) Go to the end (around Line 1680 in my version)
5) Just before the end line // ============ paste the extra code above with a blank line above and below , so the // ============ line moves down to about 1757 in my case.
6) File Save, I suggest exit WinEdt so it is forced to start afresh
7) When you re-enter WinEdt if you don't see the diagrams tab it is using the system menu instead of your personal copy, then you need to over write the master copy in WinEdt folders (back-up)
8) If you need to force a gui icon rebuild right click the tex symbols entry and press F9
9) If you don't see the icons then they were not installed in the correct %B master location so follow the old installation instructions (ignoring any old comment about gui edits)