You don't need to fly the heading, in fact that is probably an easy way to find yourself in an airspace bust.
If you only have an RBI the quick and easy way is to tune and ident as you suggest and then just mentally superimpose the position of the needle on the RBI to the DI. This will then give you the relative bearing QDM/QDR.
Position fixing on the VOR is even easier, just tune and ident then centre the needle with the flag in the direction you prefer, I tend to go with the from flag for a quick fix.