The Skywalk sole on my alt-bergs was poor on slippy/rock/icey surfaces too, It did get better as they wore in but I think maybe the only option is to see if Altberg would use a Vibram Re-Sole on your boot. My hanwags have a Vibram® Fuora sole that has lasted well so far, It grips well and physically feels softer than the skywalk.
I worked for John Bull clothing for a short while and he was the sole retailer for alt-bergs at the time, I saw a lot of different soles fitted to all sorts of boots and the work was done by Alt-berg at richmond.
here's a quote from altberg,
"At Alt-berg we are bootmakers and we appreciate good military footwear. The danner boot, the matterhorn boot, the Lowa boot and the hanwag boot are all fine examples of bootmaking and all compare well with the Alt-berg military boot range.
Hanwag boots are very similar in looks and design to the lowe boot however the fit is slightly different. The hanwag boot is a deeper last which gives slightly more volume over the foot. The hanwag military boot range is again a good selection of quality military boots and although the hanwag military boot has not been as widely distributed in the uk through military boot suppliers this is in no way a reflection of the quality of the hanwag military boot. The latest Alt-berg military boot - the combat lowe military boot is similar in design to the Lowa and hanwag military boots but the Alt-berg combat lowe boot used a micro wedge midsole for shock absorption with a full rubber rand and skywalk sole. The hanwag boot and the Lowa boot use a vibram sole with a PU shock absorbing midsole - same as the Alt-berg combat lowe military boot. The hanwag boot company also produce a range of walking boots and hiking boots. Hanwag boots are well respected all over Europe and represent good quality military boot and walking and hiking boots. The handwag military boot - the hanwag special force gtx uses a goretex bootee construction. Alt-berg are a british military boot manufacturer but we still appreciate good bootmaking and the hanwag boots are military boots made in germany and are good examples of military boot manufacture."
The only thing I don't like is the stupid "Special Forces" name, however I can't recommend these boots enough, They are not the lightest but are very comfortable. As a Non goretex I can wear them all year round with wool socks and added sorbothane insole (just prefer the extra cushioning).
I've had Danners, Matterhorn, Lowa, Altberg, 5.11, Pro-boot Issue Combat Highs.
As I have said previously I won't buy any other boot now.
Hanwag SF LX Non goretex
http://www.lansdaleltd.com/prod.php/prod/HANLX
http://www.armynnavy.com/catalog/catalog/product_info.php/cPath/323/products_id/3173
Search around for a better price you should find them for £130+ elsewhere and in stock!