I've been watching this because I was wondering the same thing. The Missus prefers 'em unsauced and it's never a big priority. A couple of weeks ago though, I rolled six slabs of spares (KC style: breast bone removed) on my 18" that I'd taken down to my parents house for a family get together. The plan was to sauce four of 'em.
Tony's tip to simply unroll, sauce, and hold in foil for at least fifteen minutes is probably the way to go. I've recently seen where bbq competitors like Harry Soo are doing something like that nowadays, claiming that the sauce will set in the foil. My sister was telling me though that she liked ribs with the sauce cooked on "sticky", and I don't know what it takes to get that without saucing the rolled ribs and putting back on the cooker a bit. All I know is, make sure you pull out your BIG basting brush out, not your wife's little bitty one. That's what I get for asking her to pack up bbq supplies before a trip! I wonder...say what if you poured a fairly thin sauce in a small pan or mixing bowl, and then rolled the rolled ribs in it with your tongs? Just something I might try next time if I want to put them back on the cooker for the sauce to set.