I'm not a landlord myself but I've dealt with quite a few landlords -- as a tenant, too, but mostly in the capacity of "maintenance".

My impression is that from the landlord's perspective, the worst outcome would be an unsuccessful attempt at putting up the rod, so that "maintenance" would have to redo it and patch stray holes in the wall. The rules/rental agreement are there both to deter the tenant from doing the damage in the first place, and to justify the landlord's lowering the boom if the tenant should go ahead and cause damage anyway.

Unless the landlord already has a score or two to settle with you, I wouldn't think they'd much mind a successful DIY curtain rod installation. It's a little harder than it looks, though, and you'd need at least some tools. I don't know how your mechanical skills are and how much relevant experience you've had. If you find yourself thinking, "What could possibly go wrong?" and you can't anticipate and prepare for at least 10 or 20 possibilities, your chances of staying out of trouble don't sound all that great.

I'd be happy to talk you through it, but only if you're fairly confident that you won't quickly find it too boring or frustrating.

An alternative might be to ask the landlord nicely if they could estimate how much longer it'll be before maintenance gets around to you.