VSS+Ultra-Edit+Brute-Force = Success
i've used ultra-edit as my code editor for 'small' projects for quite some time. it's a great tool and well worth the price, imho. i also use Visual SourceSafe quite often (i know, i know) since many shops i work with continue to favor VSS over CVS or Subversion. until now, i've never been able to get UE and VSS work work well together. UE has a feature to allow you to plug-in command line calls (including the usual %F for file names, etc.), but things always went wonky when trying to get VSS to play along. but now, i have found success!
i stumbled upon SSUE - a command line 'front' to SourceSafe's SS.EXE that can stand between VSS and Ultra-Edit and properly sort things out. it took a bit of effort to get things working. SSUE allows you to configure working directory and project directory prefixes in a way that SSUE can modify calls to VSS to make this workout. i also ran into an old problem that Windows CMD.EXE does not allow UNC names by default. there's a KB article that shows you how to fix this, too.
once i had SSUE installed, updated my registry to allow UNC names, and crafted my ultimate command line call to VSS, it all works well. i can now check files in and out directly from Ultra-Edit.