Linux: How to Press Sysreq Key in VNC/Vsphere Client?

I'm using a Vsphere client on Windows XP over a VNC link (Vinagre) from an Ubuntu 10.10 desktop running WindowMaker. It all works pretty well, but I can't find any way to press the Magic SysReq key (used to reset Linux hard). Neither Vinagre nor Vsphere has any sort of keyboard that can be pressed; trying to use the SysReq key just results in the local system being reset. Running Vinagre in full screen makes no difference.

How do I press SysReq in this combination of software? I thought that sending a BRK would help, but there's no way to do that either. I thought PrScr would do it, but don't know how. Switching from Vinagre to xtightvncviewer didn't help at all.

Am I missing something or is sending a SysReq just not possible?

UPDATE: I found information about /proc/sys/kernel/sysrq-key (which allows you to specify the key) but that seems to have been removed sometime during the Red Hat Enterprise Linux 5.x kernel lifetime. This was a feature in the mainline kernel at one time.

sysrq on ESXi VNC/Console for a redhat/fedora/debian guest:

[ctrl+alt] (keep them pressed all the time) + [space] + <release [space]> + [PrintScrn] + <sysrq> + <release [ctrl+alt]>

you might also want to try [break] instead of [printscrn]