My manual definitely does not say to run the engine while operating slides or levelers. As I read through the troubleshooting page, though, it does say that if the slides are not operating, try holding down the battery boost button while powering the slides, because the engine battery might be dead :)
I'm not currently having any problem. Just wanted to know if that battery boost button could be used while operating the slide several times during a few weeks stay at one place. So thank you all who directly answered my question.
And thank you to all who offered suggestions. I have read about the Trik-L-Start previously in this forum, and will probably add that to my motorhome when I return home after the summer. I'm not a do-it-yourselfer in this arena, so would rather have an RV tech that I know install it.