If you emerge hsfmodem you won't get the support for hda modems. I wrote to the techincal support of the linuxant and they told that they will include support in the next version, and in the mean time they provided me with the patches that will enable it to work on 2.6.18. When I asked if I am allowed to submit the patches I got the following mail: You can post the patches to bugs.gentoo.org if you want but make it clear that they are experimental patches and they might not be included exactly like that in the next version of the driver.
Created attachment 99830 [details, diff] First patch
Created attachment 99831 [details, diff] Second patch
hmmm... I would prefer to wait till official patch or next version is released. Wait! Upstream already released a patch for HDA thingie (http://www.linuxant.com/drivers/hsf/downloads-patches.php)! Please patch the latest hsfmodem with http://www.linuxant.com/drivers/hsf/full/archive/patches/hsf-7.47.00.03-alsa_2.6.15.patch and tell me if it worked for you.
It does not work for 2.6.18 - been there - done that. In file name it also sais it is for 2.6.15 (it is patch for it because driver doesn't support 2.6.25 by default.)
Upstream published your patch. I understand there are 3 conflicting patches solving the same issue and I should apply only the http://www.linuxant.com/drivers/hsf/full/archive/patches/hsf-7.47.00.03-snd_pcm_hw_param_set.patch patch. Am I right?
Today I've bumped the version to 7.47.00.05, version that contains your patch. Closed as FIXED.