[Sony Ericsson Xperia Mini, Mini Pro, Xperia Pro, A] Ticklefish:
It won't be because of the custom rom. A rom would have to be very, very different from stock for this mod not to work.

So this is your code:

<?xml version="1.0" encoding="utf-8"?>
<com.android.systemui.statusbar.StatusBarView android:orientation="vertical" android:background="@drawable/gradient" android:focusable="true" android:descendantFocusability="afterDescendants"
xmlns:android="http://schemas.android.com/apk/res/android">
<LinearLayout android:gravity="center" android:orientation="horizontal" android:layout_width="fill_parent" android:layout_height="fill_parent">
<com.android.systemui.statusbar.Clock android:textAppearance="@*android:style/TextAppearance.StatusBar.Icon" android:textSize="16.0sp" android:textStyle="normal" android:textColor="#ffffffff" android:gravity="center" android:id="@id/clock" android:paddingRight="6.0dip" android:layout_width="wrap_content" android:layout_height="fill_parent" android:singleLine="true" />
</LinearLayout>
<LinearLayout android:orientation="horizontal" android:id="@id/icons" android:layout_width="fill_parent" android:layout_height="fill_parent">
<com.android.systemui.statusbar.IconMerger android:gravity="center_vertical" android:orientation="horizontal" android:id="@id/notificationIcons" android:paddingLeft="6.0dip" android:layout_width="0.0dip" android:layout_height="fill_parent" android:layout_weight="1.0" android:layout_alignParentLeft="true" />
<LinearLayout android:gravity="center_vertical" android:orientation="horizontal" android:id="@id/statusIcons" android:paddingRight="6.0dip" android:layout_width="wrap_content" android:layout_height="fill_parent" android:layout_alignParentRight="true" />
</LinearLayout>
<LinearLayout android:orientation="horizontal" android:id="@id/ticker" android:paddingLeft="6.0dip" android:animationCache="false" android:layout_width="fill_parent" android:layout_height="fill_parent">
<ImageSwitcher android:id="@id/tickerIcon" android:layout_width="wrap_content" android:layout_height="fill_parent" android:layout_marginRight="8.0dip">
<com.android.systemui.statusbar.AnimatedImageView android:layout_width="25.0dip" android:layout_height="25.0dip" />
<com.android.systemui.statusbar.AnimatedImageView android:layout_width="25.0dip" android:layout_height="25.0dip" />
</ImageSwitcher>
<com.android.systemui.statusbar.TickerView android:id="@id/tickerText" android:paddingTop="2.0dip" android:paddingRight="10.0dip" android:layout_width="0.0dip" android:layout_height="wrap_content" android:layout_weight="1.0">
<TextView android:textAppearance="@*android:style/TextAppearance.StatusBar.Ticker" android:layout_width="fill_parent" android:layout_height="wrap_content" android:singleLine="true" />
<TextView android:textAppearance="@*android:style/TextAppearance.StatusBar.Ticker" android:layout_width="fill_parent" android:layout_height="wrap_content" android:singleLine="true" />
</com.android.systemui.statusbar.TickerView>
</LinearLayout>
<com.android.systemui.statusbar.DateView android:textAppearance="@*android:style/TextAppearance.StatusBar.Icon" android:textColor="#00000000" android:gravity="left|center" android:id="@id/date" android:background="@drawable/tw" android:paddingLeft="0.0px" android:paddingRight="0.0px" android:visibility="gone" android:layout_width="fill_parent" android:layout_height="fill_parent" android:singleLine="true" />
</com.android.systemui.statusbar.StatusBarView>

You've taken the clock line, placed it inside a new LinearLayout and put the LinearLayout above your @id/icons LinearLayout. Because that LinearLayout is as wide as the status bar, you need the clock to be in the center of it.

All you need to do is add the attribute 'android:layout_gravity="center"' to your clock line. This will center it inside the parent Layout, which is this new one you've made.

It's worth removing the 'android:paddingRight="6.0dip"' as well.

That should center the clock for you.

(You don't actually need to put the clock line inside its own LinearLayout. In the OP, I just move the clock line on its own. Technically, putting the clock line inside a Layout like this has an impact on performance. But that impact is so minimal that it's really not worth worrying about. If the code works, that's all that matters.)