It only takes a little Google-fu and common sense to inject some reality into this thread.

First off, the point of a 'travel router' is that it is small, light and portable - that is, it fits into a laptop or carry-on bag and draws very little power. Even better- maybe it sports a battery for entirely wireless operation. What a ravel router DOESN'T need is multiple ethernet ports (although these are nice, they are often redundant) and dual-band (5ghz) wifi. While this sounds like a great function, it is entirely superfluous for a real road warrior.
1) How many devices actually support 5ghz wifi? Even now, perhaps ~25%, exclusively laptops, tablets and smartphones, or game consoles released in the past ~2 years.
2) How many devices do you intend to connect to this network? More than 2 or 3? If so you're not really travelling, are you.
3) Have you ever encountered a hotel or cafe internet service that offered even 50Mbit bandwidth? If not, your wifi bandwidth will exceed that of your upstream link even with 802.11g (2.4ghz). Why do you need 150Mbit or 300Mbit or greater wireless speeds if your internet connection is only 5.. 10.. 25Mbit? Are you imaging hard drives across wifi?

The point of 5ghz wifi is that it maintains high throughput when multiple devices are connected and at longer range - travel routers have internal antennas and a typical range of 30-50 feet.

Claiming that you can not and will not trust a closed source firmware is perpetuating the worst of paranoid neckbeard behavior. Unless you only use Linux distributions you compile yourself, and use a computer with an open-source BIOS- which clearly you WON'T get from any laptop manufacturer either Windows or Macintosh, or even OEM desktop motherboard - then you're using proprietary commercial software. Claiming that a retail router manufacturer will be spying on you personally is sheer paranoia. If you have some specific commercial or legal reason to fear invasion of privacy, by all means take additional precautions but rejecting commercial devices out of hand is absurd; especially when Ed Snowden's documents have *already* demonstrated the NSA's ability to infect and control devices (HDDs in this case) at the BIOS level. So frankly, if they want *your* information they're going to get it.

Setting aside the above; no. There is NO OpenWRT support for the Dlink DIR-510L. Just because a chipset is supported does not necessarily mean a *device* is or will be. I would strongly suggest this is because D-Link products are generally shoddy quality, unreliable, and they change hardware revisions at the drop of a hat.

However, if one *is* inclined to put some effort and research into the problem, there are actual solutions to this question. TP-LINK is a well-known Taiwanese manufacturer of networking products, and has an entire series of small travel routers which are quite good performers on their own, AND also are OpenWRT-compatible. The routers in question are:

http://wiki.openwrt.org/toh/tp-link/tl-wr703n
TL-WR703N
TL-MR3020
TL-MR-3040
TL-MR10U
TL-MR11U
TL-MR12U
TL-MR13U

These models all contain common chipsets, typically 1 switchable Ethernet port (WAN/LAN), a USB port to host 3G/4G aircards and 2.4ghz wifi. MR-models also include a LiON battery pack good for 3-6 hours of use. Even with stock firmware these are quite good devices.

http://www.ebay.com/itm/181078954797

However, the WR703 and MR10 models also have several providers of hardware mods on eBay. These sellers will upgrade the onboard flash and RAM to allow additional software and package installs by flashing OpenWRT, turning them into full-feature network devices that can support VPN functions, torrent clients, USB hosts for network shares, even Asterix PBX.

So please, if you intend to make a statement at least try to follow up with some useful information.