This should ideally be done using transformations.
Alternatively, /boot/grub may be used, no grub's files there should conflict
with grub2 and they both can share the same device.map.

Lubomir Rintel <lkundrak@v3.sk>

Index: include/grub/util/misc.h
===================================================================
--- include/grub/util/misc.h.orig
+++ include/grub/util/misc.h
@@ -32,7 +32,7 @@
 /* NetBSD uses /boot for its boot block.  */
 # define DEFAULT_DIRECTORY	"/grub"
 #else
-# define DEFAULT_DIRECTORY	"/boot/grub"
+# define DEFAULT_DIRECTORY	"/boot/grub2"
 #endif
 
 #define DEFAULT_DEVICE_MAP	DEFAULT_DIRECTORY "/device.map"