We are assuming that you wish to use reverse phase and ion exchange in the same column. Ion exchange columns that run on HPLC systems do exist.
I'll assume that you know about the ion exchange HPLC columns. C18 and ion exchange have very different adsorption/retention mechanisms. It is possible to use ion pairing reagents to cause a C18 column to behave as an ion exchange column (see: http://www.chromatographyonline.com/ion-pairing-blessing-or-curse?id=&pageID=1&sk=&date= ) but there are disadvantages to this technique. There are also "mixed mode" HPLC columns available as well.