This should work:

MD "R:\DUsrData\" + @USERID ;creates user directory.
USE N: /delete ;deletes current n: drive
USE N: "\\RSERVER\RSHAREPATH\DUsrData\" + @USERID ; maps N drive.

The only difference is that kix can't do the same thing SUBST can. The N: drive would have to be mapped directly, or alternately you can just use:

SHELL "%comspec% /c subst n: r:\DUsrData\%USERNAME%"

Brian