I made scim-hangul 0.2.1-1ubuntu1 deb with the patches above and installed it.  
But, it doesn't update /etc/alternatives/xinput-ko_KR with scim if I already have nabi installed, got to remove nabi then it's fine as below.

atie@matrix:~/download/mypackage/scim-test$ sudo dpkg -i scim*.deb
Password:
(Reading database ... 216394 files and directories currently installed.)
Preparing to replace scim-hangul 0.2.1-1ubuntu1 (using scim-hangul_0.2.1-1ubuntu1_i386.deb) ...
Unpacking replacement scim-hangul ...
Setting up scim-hangul (0.2.1-1ubuntu1) ...

atie@matrix:~/download/mypackage/scim-test$ dpkg -L scim-hangul
/.
/usr
/usr/lib
/usr/lib/scim-1.0
/usr/lib/scim-1.0/1.4.0
/usr/lib/scim-1.0/1.4.0/IMEngine
/usr/lib/scim-1.0/1.4.0/IMEngine/hangul.so
/usr/lib/scim-1.0/1.4.0/SetupUI
/usr/lib/scim-1.0/1.4.0/SetupUI/hangul-imengine-setup.so
/usr/share
/usr/share/locale
/usr/share/locale/de
/usr/share/locale/de/LC_MESSAGES
/usr/share/locale/de/LC_MESSAGES/scim-hangul.mo
/usr/share/locale/fr
/usr/share/locale/fr/LC_MESSAGES
/usr/share/locale/fr/LC_MESSAGES/scim-hangul.mo
/usr/share/locale/ja
/usr/share/locale/ja/LC_MESSAGES
/usr/share/locale/ja/LC_MESSAGES/scim-hangul.mo
/usr/share/locale/ko
/usr/share/locale/ko/LC_MESSAGES
/usr/share/locale/ko/LC_MESSAGES/scim-hangul.mo
/usr/share/locale/zh_CN
/usr/share/locale/zh_CN/LC_MESSAGES
/usr/share/locale/zh_CN/LC_MESSAGES/scim-hangul.mo
/usr/share/scim
/usr/share/scim/icons
/usr/share/scim/icons/scim-hangul.png
/usr/share/doc
/usr/share/doc/scim-hangul
/usr/share/doc/scim-hangul/changelog.gz
/usr/share/doc/scim-hangul/NEWS.gz
/usr/share/doc/scim-hangul/README
/usr/share/doc/scim-hangul/TODO.Debian
/usr/share/doc/scim-hangul/copyright
/usr/share/doc/scim-hangul/changelog.Debian.gz
/etc
/etc/X11
/etc/X11/xinit
/etc/X11/xinit/xinput.d
/etc/X11/xinit/xinput.d/scim-hangul_xim
/etc/X11/xinit/xinput.d/scim-hangul_scim
atie@matrix:~/download/mypackage/scim-test$ ls -l /etc/X11/xinit/xinput.d
total 20
lrwxrwxrwx 1 root root  30 2006-02-04 09:32 ja_JP -> /etc/alternatives/xinput-ja_JP
lrwxrwxrwx 1 root root  30 2005-12-29 11:39 ko_KR -> /etc/alternatives/xinput-ko_KR
-rw-r--r-- 1 root root  65 2006-01-23 10:25 nabi
-rw-r--r-- 1 root root  52 2005-10-27 21:49 none
-rw-r--r-- 1 root root 117 2006-02-02 10:55 scim
-rw-r--r-- 1 root root 437 2006-03-05 04:26 scim-hangul_scim
-rw-r--r-- 1 root root 361 2006-03-05 04:26 scim-hangul_xim
atie@matrix:~/download/mypackage/scim-test$ ls -l /etc/alternatives/xinput-ko_KR
lrwxrwxrwx 1 root root 28 2006-03-05 04:58 /etc/alternatives/xinput-ko_KR -> /etc/X11/xinit/xinput.d/nabi
atie@matrix:~/download/mypackage/scim-test$ sudo apt-get remove --purge nabi
Reading package lists... Done
Building dependency tree... Done
The following packages will be REMOVED:
  nabi*
0 upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
Need to get 0B of archives.
After unpacking 1032kB disk space will be freed.
Do you want to continue [Y/n]? y
(Reading database ... 216393 files and directories currently installed.)
Removing nabi ...
Purging configuration files for nabi ...
atie@matrix:~/download/mypackage/scim-test$ ls -l /etc/alternatives/xinput-ko_KR
lrwxrwxrwx 1 root root 40 2006-03-05 05:12 /etc/alternatives/xinput-ko_KR -> /etc/X11/xinit/xinput.d/scim-hangul_scim