A transformation in Kentico has the possibility to be a usercontrol.
If you use the Transformation type : ASCX, you can use any ASP.NET control you want.
Including the predefined Kentico usercontrols.
<cms:BizForm runat="server" ID="BizForm" FormName="YourBizFormCodeName" EnableViewState="false" AlternativeFormFullName="BizForm.YourBizFormCodeName.YourBizFormAlternativeFormName"/>
You can also give an AlternativeFormFullName to specify the alternative form you wish to use.