ok..try this way:
open a MIUI theme you already got with winrar and don't delete mtz
open my icon archive with winrar
now..in the theme open the icon folder..(if there is..if not download signs mtz iconpack from miui android...) then search for the icon you want tranform(example for phone search com.android.phone....or com.android.contacs...i don't exactly remember) copy the file name to the retro icon with the phone.
do this passage to every icon...
Then right click on the original theme mtz--"open with winrar"
select all folder except "icon" folder and the manifest.xml file..now press canc
once deleted everything:
open icons archive
delete every thing
drag retro with modified name in the folder
press back arrow
open manifest xml with text editor
modify name, version author but not the uiversion
press X on manifest...save? yes!
close winrar
rename theme.mtz something like retro.icon.mtz or what you prefere..
copy to your sd
theme manager
theme setting
icons
chose your's
you've done..

Hope you now understand why i got no time to do something i really don't need
hope i helped you with this little guide
IF NOT google for what you're lookin for...you'll find tons of guide that explain you better how to do..

seeYa!