What's the best way to flush new a/c compressor on a 87 300SDL?

[airfoill]

I'm about ready to reconvert from R-134 back to R-12 and purchased a new Denso compressor that already has oil installed compatable to the R-134. What's the best way to remove that oil from the unit and replace with mineral oil compatable with R-12? AC flush? Run mineral oil through compressor over and over till flush? What do you guys do when flushing compressors?

Also had a follow up question. After a complete flush of the AC system, when replacing the oil, do you place it all in the compressor or split it up at various locations along inside hoses while reassembling system?

Thanks!

Herb