2007 Nav System Workaround ???

Ok, I'm new to this, but I tried to search the topic without finding any answers, so please don't get mad if this question gets asked again and again:

Is there a way to operate the Nav system in a 2007 Suburban/Yukon/Tahoe while driving???

Once the vehicle is in motion, the nav system will no longer let you input addresses, the XM radio will not let you browse categories, and (may be a seperate issue) you cannot watch a dvd while the vehicle is in drive. I don't really care about watching DVDs while driving, there are way too many distractions on the road as it is, but I would like to be able to use my nav system without having to pull over!!!!

Any help would be greatly appreciated - Michael