Sad, but true. You could use Remote Desktop to your main machine and just use the tablet as a thin client. You can even use the cross-compiler for ARM and produce executables that will run on (jailbroken) RT systems, which could then be copied back down from Remote Desktop for local execution. However, to the best of my knowledge, there is no working C++ (or even C) compiler that will run on RT right now.
It *might* be possible to run MSVC through Mamaich's x86 compatibility layer, which (if configured to produce ARM binaries) would let you compile code (slowly) that would run natively on the tablet. I don't know if that's practical, though; the dynamic recompilation is probably up to it (at the machine level, compilation is surprisingly simple given how complex it is at the algorithm level) but MSVC probably requires libraries and/or system calls which aren't implemented yet. Normally I'd say that's a great thing to request focusing on, but the public build of the emulator hasn't been updated in many months...
Win8/Windows RT projects:
List of desktop apps for hacked RT devices
Native Access WebServer and Libraries
WP8 Interop Unlocks
Storage Cleanup tool
XapHandler, Root Webserver, OEM Marketplace XAPs, Bookmarklets collection (Find On Page), Interop-unlock hacks.
Do not private message me with questions that should have been posted on the forum!
Not only are you wasting your time - I'm not going to bother writing an answer to such a question for only one person - but I will probably block you from PMing me in the future as well.