'be comfortable with using' is correct and usable in written English.
You can use this phrase when you are talking about someone becoming accustomed or gaining familiarity with a particular method, process, or tool. For example, "As you learn to use the new software, you'll soon become comfortable with using the features."
Social networks and advertisers know far more about us than we should be comfortable with, using information we freely give them.
So those are the two things you have to be comfortable with using.
Before the public can be comfortable with using a block cipher, it needs to gain public trust on its level of security.
Thus, LBVS becomes straightforward for scientists who may not be comfortable with using the command line interface.
"That doesn't mean that they have to write new programs themselves," he says, "but they have to be comfortable with using computers in increasingly sophisticated ways".
People seem to be comfortable with using TwitPic despite its lack of features (which is being worked on, by the way), and I doubt more features will make them switch any time soon.
The majority of students are comfortable with using peer physical examination, when sensitive areas are excluded.
Ms. Paulsen said the foundation was "comfortable" with using the Pravachol name and with Bristol-Myer's financing much of the campaign.
I also want my children to be adept at technology so they're comfortable with using it at school and, someday, in the workplace.
Men would have carried swords as a matter of course, and been comfortable with using them, or at least threatening to, and people would almost certainly have witnessed more violence on a daily basis.
No. "We need to look at them carefully to make sure we're comfortable with any steps that we take". This is like the captain of the Titanic looking carefully at his lifeboats to make sure he's comfortable with using them as the ship starts sinking.
