I would simply use one of the already created WiX UI and override the sequence (make it higher so that it will override the previous setting):
<Product>
...
<UI>
<UIRef Id="WixUI_InstallDir" />
<!-- Skip license dialog -->
<Publish Dialog="WelcomeDlg"
Control="Next"
Event="NewDialog"
Value="InstallDirDlg"
Order="2">1</Publish>
<Publish Dialog="InstallDirDlg"
Control="Back"
Event="NewDialog"
Value="WelcomeDlg"
Order="2">1</Publish>
</UI>
<Property Id="WIXUI_INSTALLDIR" Value="INSTALLFOLDER" />
...
</Product>
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…