help with some specialty grains

I am trying to convert an all grain recipe to partial mash and a good portion of the grain bill is

Munich, Rye, and Roasted Barley.

My question is can these be mashed without the base malts or do they need the enzymes from the base malts for conversion.

Beersmith did not say anything about it and I am still learning about grain so I just wanted to check before purchasing.

I plan to replace the six pounds of base with DME and make a mini mash out of the others.

The recipe is "Brighad's Red Irish Rye" from the recent Zymurgy issue.
Ingredients:
------------
Amount Item Type % or IBU
0.25 lb Rice Hulls (0.0 SRM) Adjunct 2.04 %
6.00 lb Pale Malt, Maris Otter (3.0 SRM) Grain 48.98 %
3.25 lb Munich Malt (9.0 SRM) Grain 26.53 %
2.50 lb Rye Malt (4.7 SRM) Grain 20.41 %
0.25 lb Roasted Barley (300.0 SRM) Grain 2.04 %
1.00 oz Challenger [7.50 %] (60 min) Hops 18.3 IBU
1.00 oz Fuggles [4.50 %] (15 min) Hops 5.4 IBU
1.10 items Whirlfloc Tablet (Boil 15.0 min) Misc
2 Pkgs Nottingham Yeast (Lallemand #-) Yeast-Ale


Mash Schedule: My Mash
Total Grain Weight: 12.25 lb

Munich and rye will convert themselves, so no problem there. Roasted barley doesn't need to be mashed, so you should be fine.

EDIT: Also note that it is possible to get malt extract that is produced from Munich malt, so if you can find it, you would only have to mash the rye and roasted barley. (Might make it easier to find an appropriately large mash tun.)

Thanks, I have a 3 gallon cooler I am using as a MLT for now. My trial run with it was BM's centinneal blonde PM version last week and I found that I can safely use about 6 -6.5 pounds of grain in it. I am trying to get as much of the grain bill to be actual grain as possible until I move at the end of the year and get to work on my own full blown AG system. Hoping doing these partials will get my techique and process down by then.

Sounds ideal -- best of luck!