Did the inhabitants of Shechem, mentioned in parshah Vayishlach, convert to Judaism?
The Torah Lodaas sheet published weekly by Rabbi Matis Blum, in its Vayishlach 2014 issue, quotes the G'riz as follows (in my own translation):
In truth, the response of Yaakov's sons was not merely to fool [the Shechemites] into circumcising themselves so they'd be able to kill them. Rather, it was a truthful response to Chamor's words: he had told them "you'll intermarry with us", and to this they replied that marriage is forbidden so long as [the Shechemites] are uncircumcised. Only "if you will be like us, to circumcise every male", meaning they'd be like them in that the circumcision would be for the sake of conversion, as the verse continues "and we will be one nation", i.e. that they'd convert and become Israelites, then "we will give our daughters to you", because then intermarriage with them would be permitted. Thus, there was no deception in their response, which is why Onk'lus translates [the word normally translated "with deception" as] "with wisdom".
But [the Shechemites] did not understand their intent, so circumcised themselves with a plain circumcision [i.e. not with intent to convert].
According to this, no, they didn't convert.
Rabbi Sorotzkin, in Oznayim Latorah, says that based on the response of Shechem (the prince), they were "geirei arayos" (עריות) which is worse than "Geirei Ari" (ארי) used for the Shomronim who converted because of a fear of lions. This means they "converted" to be able to get the "Jewish women" which is invalid. Both the Bnai Yisrael and the people of Shechem knew that they were not "converting" legitimately from the beginning. The only thing was that the Bnai Shechem did not know that the Bnai Yisrael had realized what they were up to from the beginning.