you could try this GUI it got twinview working for me with a 128mb mx440 in suse pro 9.0 think it may even be a sparkle
just watch the metamodes in the GUI it insist on metamodes before it will save the xf86config and it asks for ie 800x600 @ ??? x ???
leaving the second section blank after the @ it inserts into the config
metamodes "800x600 @x, 800x600 @x"
well that will just crash X so edit the metamodes line in XF86.Config after saving it "800x600,800x600" should work fine or whatever res you want set.
unless of course you know what is suposed to go in the @ ???x??? portion.
if you still want monitor or tv only then save your current XF86Config that is working for your monitor and ill post my tvout only sections then you can just switch the configs and restart X.
there are other methods plenty of them posted here to have crt,crt and switch methods between multiple monitors or tvs,
just search "tvout" "twinveiw" "xf86config" its all i did. and yes i failed to config twinveiw even from examples but I can get tvout only manual and the GUI sorted my crt,TV