How to programmatically alter an apps size, with DIP instead of PX

How to programmatically alter an apps size, with DIP instead of PX

I've searched and found an exceptional amount of answers to this, but none
that will show how they are inserted into the activity.
My activity has a tabsadapter and viewpager (fragmentpageradapter). That's
it. And I've set it to be styled as a dialog, like this
<style name="Theme.PopupTheme" parent="android:Theme.Holo.Light.Dialog">
<item name="android:windowIsFloating">false</item>
<item name="android:windowContentOverlay">@null</item>
<item name="android:windowSoftInputMode">stateAlwaysHidden</item>
<item name="android:windowActionModeOverlay">true</item>
<item name="android:windowIsTranslucent">true</item>
<item name="android:windowNoTitle">false</item>
<item name="android:windowActionBar">true</item>
<item name="android:backgroundDimEnabled">true</item>
<item name="android:padding">2sp</item>
<item name="android:divider">@drawable/transparent</item>
Now, this works just fine except that it takes up the full size of the
display with barely any transparency on the sides and bottom. There is no
layout for this activity, just a viewpager xml
<android.support.v4.view.ViewPager
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/viewPager"
android:layout_width="match_parent"
android:layout_height="match_parent" />
Because of this I'm tied to sizing the app programmatically. I found that
I can only manage this (with my level of skill) by setting it with pixels.
Which can look good if it was meant for a certain device, but the app
looks atrocious on my Nexus 10 compared to my S3 when and vice-versa
depending on the amount of pixels I set.
How can I do this programmatically with dip?