I don't have it installed locally, but here is the code that actually does it, it definitely seems promising...
FadeClient(client, r, g, b, a)
{
new Handle:hFadeClient = StartMessageOne("Fade",client)
if (GetUserMessageType() == UM_Protobuf)
{
new color[4]
color[0] = r
color[1] = g
color[2] = b
color[3] = a
PbSetInt(hFadeClient, "duration", 0)
PbSetInt(hFadeClient, "hold_time", 0)
PbSetInt(hFadeClient, "flags", (FFADE_PURGE|FFADE_STAYOUT))
PbSetColor(hFadeClient, "clr", color)
}
else
{
BfWriteShort(hFadeClient, 0)
BfWriteShort(hFadeClient, 0)
BfWriteShort(hFadeClient, (FFADE_PURGE|FFADE_STAYOUT))
BfWriteByte(hFadeClient, r)
BfWriteByte(hFadeClient, g)
BfWriteByte(hFadeClient, b)
BfWriteByte(hFadeClient, a)
}
EndMessage()
}