You would need to edit one of the navigraph files in the FSX/SE/P3D\Captain_Sim\navigation folder. I did show how to do it in either the 767 Captain, or 757 Captain forum, and you would need to search for the topic.

That would be the one.

Rapidshare changed how you could share files (they suddenly decided that they would be deleted after a short time).

I will see if I can find the file on my PC (or maybe I have it on Dropbox). My backup HDD failed, and I lost a lot of FSX/P3D stuff - one needs backups of backups these days.

EDIT. I found the file in my Dropbox, but even they have changed how to share files, so I will describe what you need to edit.

Go to the FSX/P3D\Captain_Sim\navigation folder

Open the Airports.db with Notepad.
Press CTRL+F, then enter VHHH in the search field, then add the following below the VHHH entry:

22;VHHX;22.304401;114.216064

Save the changes (CTRL+S).

Open the Runways.db with Notepad.
Press CTRL+F, then enter VHHH in the search field, then add the following below the VHHH entries:

VHHX;3.0;110.90;22.305500;11122;114.214500;13;135.0
VHHX;3.0;110.75;22.305500;11122;114.214500;31;315.0

Save the changes (CTRL+S).

That's all you need to do. I never found any info for adding SIDS/STARS/TRANS to the files, so you need to find your own way there.
The ILS frequencies/headings are
RWY 13: 110.90/135
RWY 31: 110.75/315

NOTE. BACKUP THE AIRPORTS.DB, AND RUNWAYS.DB FILES BEFORE MAKING ANY CHANGES.
Updating the navigraph data each month, means you would need to do all of this again after the update!