To add to what Anil said, I think the lack of strategic thinking here is glaring. Basically some people have manufactured a consensus that amending HMA would be good. I know that majority of Jats want HMA amended in line with their customs (You don't need this poll to tell you that). It is unfortunate that the masses were led in that direction instead of introspecting on what's going on at grass roots level. There is a mass scale cultural upheaval (TV, nuclear families, media, westernization, etc.) and the moral authority of these customs is caving in. Probably even mentioning that is taboo, so the convenient option of HMA is chosen. Anyways, I'd be pragmatic and I think the need of the hour is to give masses what they want to calm them down- through an amendment of HMA. It is a political solution to avoid a problem from getting worse. If I was talking to the govt., that's what I'd say.
But how do we go about it? Funnily, we want all like minded people to get together and then talk about what they already agree- amend the HMA, support the Khaps, show them these poll results, a crude draft, moral support, etc. To put it bluntly, all of us agreeing between ourselves is not going to make an iota of difference to the decision-makers. There is a large scale media onslaught on the Khaps and anything associated with Jats is being shown in a negative light. The govt. is giving in to that pressure as we speak. I see absolutely no move for amendment of HMA, while there is talk of new laws to deal with honour killings, Khaps, etc.
To amend the HMA, first and foremost, the public image of the community needs to be taken care of. An extremist who shouts about the great customs and his eagerness to kill for them is the last guy you want. Such people give the world a stick to beat us with. They also try to hijack the community by provoking them with outrageous theories. As in any battle, a foolish supporter is more dangerous to you than an intelligent opponent. This is a battle for mindspace and can be won by sane arguments only. The community needs to first unambigously state that it is against any kind of honour killing. It is important to defang the opposition (and important as a principle as well). It then needs to put forward a logical case for amendment of HMA. That there is precedence for allowing other communities to be governed by their personal laws. That the community considers a kinship equivalent to a family within a gotra. And like we don't define the kinship for anyone else (who marry in their cousins), no one should define kinship for us. To point out that media rants against "medieval, barbaric believes" is precisely doing that and it has no space in a secular India that gives every community the right to practise their culture and customs. Also point out the incoherence with Gandhian philosophy of being guided by India's moral norms, especially its villages. And the ridiculousness of forcing western individualist culture on a traditional rural India that puts emphasis on a community-oriented way of life and has its own indigenous social norms. We can similarly, logically demolish arguments like "Talibani fatwas" and much other misinformation in media.
We should never give wrong arguments that only weaken our case. "Scientific basis" is the most popular one and won't find favor when grilled on principles of science. Anything about our superiority or any form of caste jingoism is going to be very counterproductive.
Then you have to think of what the opposition is going to be like- people would talk about individual's rights being contravened. And the answer to that is that there are provisions in the constitution for other communities and same would apply here as well. No one is forced to remain in the community, those who want to marry against the customs can do so, but not as a Jat. Any questions on medieval or barbaric customs have to be tackled in a cultural context, on how many other communities (even Parsis who are everyone's favorite) have their own practises.
We need to co-opt non-Jat organizations who work at grassroots level and have a voice in the media. Madhu Kishwar of Manushi is one of them. She even held a conference of Khap leaders to discuss this issue. Genuine social activists like her need to be impressed with sane arguments.
And a lot can be said about political strategy as well. But unfortunately, people are busy showing their support and talking about a draft (not working), lest someone doubts their Jat credentials. There are 2 drafts here, one by me; and I have no shame in saying both are pretty much useless as far as "trying to get HMA amended" is concerned. (It was useful to me personally to work my brain a bit)