Follow up, a quick test on my system show that your commands should work:
[root@sme74test php.ini]# db configuration show php
php=service
AllowUrlFopen=Off
status=enabled
[root@sme74test php.ini]# cp /etc/php.ini /tmp/
[root@sme74test php.ini]# db configuration setprop php MemoryLimit 128M
[root@sme74test php.ini]# db configuration setprop php PostMaxSize 128M
[root@sme74test php.ini]# db configuration setprop php UploadMaxFilesize 128M
[root@sme74test php.ini]# db configuration show php
php=service
AllowUrlFopen=Off
MemoryLimit=128M
PostMaxSize=128M
UploadMaxFilesize=128M
status=enabled
[root@sme74test php.ini]# expand-template /etc/php.ini
[root@sme74test php.ini]# diff -u /tmp/php.ini /etc/php.ini
--- /tmp/php.ini 2009-02-16 19:28:06.000000000 +0100
+++ /etc/php.ini 2009-02-16 19:29:09.000000000 +0100
@@ -31,7 +31,7 @@
highlight.html = #000000
expose_php = On
max_execution_time = 30
-memory_limit = 32M
+memory_limit = 128M
mysql.allow_persistent = On
error_reporting = E_ALL & ~E_NOTICE
display_errors = Off
@@ -44,7 +44,7 @@
variables_order = "EGPCS"
register_globals = Off
register_argc_argv = On
-post_max_size = 20M
+post_max_size = 128M
gpc_order = "GPC"
magic_quotes_gpc = On
magic_quotes_runtime = Off
@@ -60,7 +60,7 @@
extension_dir = /usr/lib/php4
enable_dl = On
file_uploads = On
-upload_max_filesize = 10M
+upload_max_filesize = 128M
allow_url_fopen = Off
extension=eaccelerator.so
[root@sme74test php.ini]#
So I guess your webserver did not restart.